27 (twenty-seven; Roman numeral XXVII) is the natural number following 26 and preceding 28.

In mathematics

* Twenty-seven is a

cube In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. Viewed from a corner it is a hexagon and its net is usually depicted as a cross. The cube is the only r ...

of 3:

3^3=3\times 3\times 3

. 27 is also ²3 (see

tetration In mathematics, tetration (or hyper-4) is an operation based on iterated, or repeated, exponentiation. There is no standard notation for tetration, though \uparrow \uparrow and the left-exponent ''xb'' are common. Under the definition as rep ...

). There are exactly 27 straight lines on a smooth

cubic surface In mathematics, a cubic surface is a surface in 3-dimensional space defined by one polynomial equation of degree 3. Cubic surfaces are fundamental examples in algebraic geometry. The theory is simplified by working in projective space rather th ...

, which give a basis of the

fundamental representation In representation theory of Lie groups and Lie algebras, a fundamental representation is an irreducible finite-dimensional representation of a semisimple Lie group or Lie algebra whose highest weight is a fundamental weight. For example, the defini ...

of the E₆

Lie algebra In mathematics, a Lie algebra (pronounced ) is a vector space \mathfrak g together with an Binary operation, operation called the Lie bracket, an Alternating multilinear map, alternating bilinear map \mathfrak g \times \mathfrak g \rightarrow ...

. 27 is also a

decagonal number A decagonal number is a figurate number that extends the concept of triangular and square numbers to the decagon (a ten-sided polygon). However, unlike the triangular and square numbers, the patterns involved in the construction of decagonal number ...

. * In

decimal The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

, it is the first

composite number A composite number is a positive integer that can be formed by multiplying two smaller positive integers. Equivalently, it is a positive integer that has at least one divisor other than 1 and itself. Every positive integer is composite, prime, ...

not divisible by any of its digits. * It is the

radix In a positional numeral system, the radix or base is the number of unique digits, including the digit zero, used to represent numbers. For example, for the decimal/denary system (the most common system in use today) the radix (base number) is t ...

(base) of the

septemvigesimal There are many different numeral systems, that is, writing systems for expressing numbers. By culture / time period By type of notation Numeral systems are classified here as to whether they use positional notation (also known as place-value ...

positional Positional notation (or place-value notation, or positional numeral system) usually denotes the extension to any base of the Hindu–Arabic numeral system (or decimal system). More generally, a positional system is a numeral system in which the ...

numeral system A numeral system (or system of numeration) is a writing system for expressing numbers; that is, a mathematical notation for representing numbers of a given set, using Numerical digit, digits or other symbols in a consistent manner. The same s ...

. * 27 is the only positive integer that is 3 times the sum of its digits. * In a

prime reciprocal magic square A prime reciprocal magic square is a magic square using the decimal digits of the reciprocal of a prime number. Consider a unit fraction, like 1/3 or 1/7. In base ten, the remainder, and so the digits, of 1/3 repeats at once: 0.3333... . H ...

of the multiples of , the magic constant is 27. * In the

Collatz conjecture The Collatz conjecture is one of the most famous unsolved problems in mathematics. The conjecture asks whether repeating two simple arithmetic operations will eventually transform every positive integer into 1. It concerns sequences of integ ...

(aka the "

3n+1

conjecture"), a starting value of 27 requires 111 steps to reach 1, more than any number smaller than it. * The unique simple formally real

Jordan algebra In abstract algebra, a Jordan algebra is a nonassociative algebra over a field whose multiplication satisfies the following axioms: # xy = yx (commutative law) # (xy)(xx) = x(y(xx)) (). The product of two elements ''x'' and ''y'' in a Jordan alg ...

, the exceptional Jordan algebra of self-adjoint 3 by 3 matrices of

quaternion In mathematics, the quaternion number system extends the complex numbers. Quaternions were first described by the Irish mathematician William Rowan Hamilton in 1843 and applied to mechanics in three-dimensional space. Hamilton defined a quatern ...

s, is 27-dimensional. * In decimal, it is a

Smith number In number theory, a Smith number is a composite number for which, in a given number base, the sum of its digits is equal to the sum of the digits in its prime factorization in the given number base. In the case of numbers that are not square-f ...

and a

Harshad number In mathematics, a harshad number (or Niven number) in a given number base is an integer that is divisible by the sum of its digits when written in that base. Harshad numbers in base are also known as -harshad (or -Niven) numbers. Harshad numbers ...

. * It is located at the twenty-eighth (and twenty-ninth) digit after the decimal point in . (3.141592653589793238462643383279...). If one starts counting with 0, it is one of few know
self-locating strings in pi
* In decimal, 27 is the sum of the numbers between and including its digits (

2+3+4+5+6+7=27

). * There are 27

sporadic group In mathematics, a sporadic group is one of the 26 exceptional groups found in the classification of finite simple groups. A simple group is a group ''G'' that does not have any normal subgroups except for the trivial group and ''G'' itself. The ...

s, if the

Tits group In group theory, the Tits group 2''F''4(2)′, named for Jacques Tits (), is a finite simple group of order : 211 · 33 · 52 · 13 = 17,971,200. It is sometimes considered a 27th sporadic group. ...

is included. * If one cyclically rotates the digits of a three-digit number that is a multiple of 27, the new number is also a multiple of 27. For example, 378, 783, and 837 are all divisible by 27. * Any multiple of 27 with 000 or 999 inserted yields another multiple of 27. For example, 20007, 29997, 50004, and 59994 are all multiples of 27. * Any multiple of 27 can be mirrored and spaced with a zero each for another multiple of 27. For example, 27 and 702, 54 and 405, and 378 and 80703 are all multiples of 27. * In

senary A senary () numeral system (also known as base-6, heximal, or seximal) has six as its base. It has been adopted independently by a small number of cultures. Like decimal, it is a semiprime, though it is unique as the product of the only two con ...

, one can readily test for divisibility by 43 (decimal 27) by seeing if the last three digits of the number match 000, 043, 130, 213, 300, 343, 430, or 513. * 27 is divisible by the number of

prime numbers A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways ...

below it.

In science

*The

atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, pr ...

. *The atomic weight of the only stable isotope of

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...

. *

Dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

is thought to make up 27% of the universe.

Astronomy

*The

Messier object The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters''). Because Messier was only int ...

M27, a

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

7.5

planetary nebula A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Vulpecula Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle (an ...

, also known as the

Dumbbell Nebula The Dumbbell Nebula (also known as the Apple Core Nebula, Messier 27, and NGC 6853) is a planetary nebula (nebulosity surrounding a white dwarf) in the constellation Vulpecula, at a distance of about 1360 light-years. It was the first such nebula ...

. *The

New General Catalogue The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and ...

object

NGC 27 NGC commonly refers to: * New General Catalogue of Nebulae and Clusters of Stars, a catalogue of deep sky objects in astronomy NGC may also refer to: Companies * NGC Corporation, name of US electric company Dynegy, Inc. from 1995 to 1998 * Nati ...

, a

spiral galaxy Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''Andromeda constellation. *The

Saros number The saros () is a period of exactly 223 synodic months, approximately 6585.3211 days, or 18 years, 10, 11, or 12 days (depending on the number of leap years), and 8 hours, that can be used to predict eclipses of the Sun and Moon. One saros period ...

of the

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six month ...

series, which began on March 9, 1993 BCE and ended on April 16, 713 BCE. The duration of Saros series 27 was 1,280.1 years, and it contained 72 solar eclipses. Further, the Saros number of the

lunar eclipse A lunar eclipse occurs when the Moon moves into the Earth's shadow. Such alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth ...

series, which began on July 28, 1926 BCE and ended on January 23, 411 BCE. The duration of Saros series 27 was 1532.5 years, and it contained 86 lunar eclipses.

Electronics

*The type 27

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...

(valve), a

triode A triode is an electronic amplifying vacuum tube (or ''valve'' in British English) consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode). Developed from Lee De Forest's 19 ...

introduced in 1927, was the first tube mass-produced for commercial use to incorporate an

indirectly heated cathode A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as a ...

. This made it the first vacuum tube that could function as a

detector A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...

in AC-powered radios. Prior to the introduction of the 27, home radios were powered by a set of three or more

storage batteries A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or prima ...

with

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...

s of 3 volts to 135 volts.

In language and literature

*The number of letters in the

Spanish alphabet Spanish orthography is the orthography used in the Spanish language. The alphabet uses the Latin script. The spelling is fairly phonemic, especially in comparison to more opaque orthographies like English, having a relatively consistent mapping ...

. *The number of books in the New Testament.

In astrology

*27

Nakṣatra Nakshatra ( sa, नक्षत्रम्, translit=Nakṣatram) is the term for lunar mansion in Hindu astrology and Indian Astronomy. A nakshatra is one of 27 (sometimes also 28) sectors along the ecliptic. Their names are related to a ...

or lunar mansions in Hindu astrology.

In art

Movies

*''Summer'', or ''

27 Missing Kisses ''27 Missing Kisses'' ( ka, 27 დაკარგული კოცნა, ), also known as ''Summer''. is a 2000 Georgian film directed by Nana Djordjadze that contains elements of fantasy or magical realism. It was featured during the Directo ...

'' *''Chapter 27-I'' *''

27 Dresses ''27 Dresses'' is a 2008 American romantic comedy film directed by Anne Fletcher, written by Aline Brosh McKenna, and starring Katherine Heigl and James Marsden. The film was released in Australia on January 10, 2008, and in the United States on J ...

'' *''Number 27'' (written by

Michael Palin Sir Michael Edward Palin (; born 5 May 1943) is an English actor, comedian, writer, television presenter, and public speaker. He was a member of the Monty Python comedy group. Since 1980, he has made a number of travel documentaries. Palin w ...

)

Music

*"27", a song by Fall Out Boy on the album ''

Folie à Deux Folie à deux ('folly of two', or 'madness haredby two'), also known as shared psychosis or shared delusional disorder (SDD), is a collection of rare psychiatric syndromes in which symptoms of a delusional belief, and sometimes hallucinations, ...

'' *"27", a song by Passenger on the album '' Whispers'' *"27", a song by Title Fight on the album ''Shed''. *" 27", a song by Biffy Clyro on the album ''Blackened Sky'' *"27", a song on Machine Gun Kelly's album '' Bloom'' *"27 Jennifers", a song by Mike Doughty on the album ''

Rockity Roll ''Rockity Roll'' was the third solo recording released by Mike Doughty after the breakup of his former band, Soul Coughing. It is a six-song EP which he recorded in New York City over two days in May 2003 at Pat Dillett's tiny, windowless cubby ...

'' *'' 27'', an album by South Korean singer Kim Sung-kyu *'' 27'', an album by Argentine rock band Ciro y los Persas *''Twenty-Seven'', an album by

The Adicts The Adicts are a British punk rock band from Ipswich, Suffolk, England. One of the most popular punk rock bands in the 1980s, they were often in the indie charts during that decade. The Adicts originated as The Afterbirth in late 1975 but n ...

. *French rapper

Kaaris Okou Gnakouri Armand Olivier (; born 30 January 1980), better known by his stage name Kaaris (, ; stylized as KΛΛRIS), is a Ivorian-born French rapper, record producer, composer and actor. ''Or Noir'', his major album on Therapy Music / AZ / U ...

' signature number is 27, from his zipcode 93270. *"Twenty Seven Strangers" by Villagers. * 27, a Boston-based band *'' 27'', an opera by composer Ricky Ian Gordon and librettist Royce Vavrek *

27 Club The 27 Club is an informal list consisting mostly of popular musicians, artists, actors, and other celebrities who died at age 27. Although the claim of a "statistical spike" for the death of musicians at that age has been refuted by scientific ...

, a list of popular musicians, artists, or actors who died at age 27

Other

*The Minneapolis-based artist Deuce 7 (a.k.a. Deuce Seven, Twenty Seven, 27). *27 is the number of years it takes for Pennywise to return

In sports

* The value of all the colors in

snooker Snooker (pronounced , ) is a cue sports, cue sport played on a Billiard table#Snooker and English billiards tables, rectangular table covered with a green cloth called baize, with six Billiard table#Pockets 2, pockets, one at each corner and o ...

add up to 27. * The number of outs in a regulation baseball game for each team at all adult levels, including professional play, is 27. * The

New York Yankees The New York Yankees are an American professional baseball team based in the Boroughs of New York City, New York City borough of the Bronx. The Yankees compete in Major League Baseball (MLB) as a member club of the American League (AL) Amer ...

have won 27

World Series The World Series is the annual championship series of Major League Baseball (MLB) in the United States and Canada, contested since 1903 between the champion teams of the American League (AL) and the National League (NL). The winner of the World ...

championships, the most of any team in the

MLB Major League Baseball (MLB) is a professional baseball organization and the oldest major professional sports league in the world. MLB is composed of 30 total teams, divided equally between the National League (NL) and the American League (AL), ...

In other fields

Twenty-seven is also: * The

is a term used to refer to popular musicians who have died at the age of 27. * A-27, American attack aircraft. * The total number of letters in the

Hebrew alphabet The Hebrew alphabet ( he, wikt:אלפבית, אָלֶף־בֵּית עִבְרִי, ), known variously by scholars as the Ktav Ashuri, Jewish script, square script and block script, is an abjad script used in the writing of the Hebrew languag ...

(22 regular letters and 5 final consonants). * The code for international direct-dial phone calls to

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. * The name of a cigarette,

Marlboro Marlboro (, ) is an American brand of cigarettes, currently owned and manufactured by Philip Morris USA (a branch of Altria) within the United States and by Philip Morris International (now separate from Altria) outside the US. The largest Marl ...

Blend No. 27. * Alternate name for ''The Hunt'', a book by

William Diehl William Diehl (; December 4, 1924 – November 24, 2006) was an American novelist and photojournalist. Biography Diehl was a successful photographer and journalist, when he began his novel-writing career at 50. His first novel, ''Sharky's Ma ...

. * The number of the French department

Eure Eure () is a department in Normandy in Northwestern France, named after the river Eure. Its prefecture is Évreux. In 2019, Eure had a population of 599,507.Abbé Faria Abbé Faria (), or Abbé (Abbot) (born José Custódio de Faria; 31 May 1756 – 20 September 1819), was a Luso- Goan Catholic monk who was one of the pioneers of the scientific study of hypnotism, following on from the work of Franz Mesmer ...

's prisoner number in the book ''

The Count of Monte Cristo ''The Count of Monte Cristo'' (french: Le Comte de Monte-Cristo) is an adventure novel written by French author Alexandre Dumas (''père'') completed in 1844. It is one of the author's more popular works, along with ''The Three Musketeers''. Li ...

''. * One of the

anthropomorphic Anthropomorphism is the attribution of human traits, emotions, or intentions to non-human entities. It is considered to be an innate tendency of human psychology. Personification is the related attribution of human form and characteristics t ...

math symbols

Lisa Simpson Lisa Marie Simpson is a fictional character in the animated television series ''The Simpsons''. She is the middle child and most accomplished of the Simpson family. Voiced by Yeardley Smith, Lisa was born as a character in ''The Tracey Ullman Sh ...

imagines talking to her in ''

The Simpsons ''The Simpsons'' is an American animated sitcom created by Matt Groening for the Fox Broadcasting Company. The series is a satirical depiction of American life, epitomized by the Simpson family, which consists of Homer, Marge, Bart, Lisa, ...

'' episode " Girls Just Want to Have Sums", which, instead of offering the expected pun-based

aphorism An aphorism (from Greek ἀφορισμός: ''aphorismos'', denoting 'delimitation', 'distinction', and 'definition') is a concise, terse, laconic, or memorable expression of a general truth or principle. Aphorisms are often handed down by tra ...

, rather unhelpfully only says "twenty seven". * In

Stephen King Stephen Edwin King (born September 21, 1947) is an American author of horror, supernatural fiction, suspense, crime, science-fiction, and fantasy novels. Described as the "King of Horror", a play on his surname and a reference to his high s ...

's novel '' It'', It returns every 27 years to

Derry Derry, officially Londonderry (), is the second-largest city in Northern Ireland and the fifth-largest city on the island of Ireland. The name ''Derry'' is an anglicisation of the Old Irish name (modern Irish: ) meaning 'oak grove'. The ...

. * 27 is the number of bones in the human

hand A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "h ...

.Steve Jenkins, ''Bones'' (2010), * Number of planets needed to fuel the Reality Bomb in the episodes "

The Stolen Earth "The Stolen Earth" is the twelfth episode of the Doctor Who (series 4), fourth series and the 750th overall episode of the British science fiction on television, science fiction television series ''Doctor Who''. It was first broadcast on BBC One ...

" and "

Journey's End ''Journey's End'' is a 1928 dramatic play by English playwright R. C. Sherriff, set in the trenches near Saint-Quentin, Aisne, towards the end of the First World War. The story plays out in the officers' dugout of a British Army infantry comp ...

" of ''Doctor Who'' (series 4).

References

* Wells, D. ''

The Penguin Dictionary of Curious and Interesting Numbers ''The Penguin Dictionary of Curious and Interesting Numbers'' is a reference book for recreational mathematics and elementary number theory written by David Wells. The first edition was published in paperback by Penguin Books in 1986 in the UK, ...

'' London: Penguin Group. (1987), p. 106.
Mystery of the number 27
- Large collection of 27 related trivia and facts.

from the

Prime Pages The PrimePages is a website about prime numbers maintained by Chris Caldwell at the University of Tennessee at Martin. The site maintains the list of the "5,000 largest known primes", selected smaller primes of special forms, and many "top twenty" ...

The 27 Project
- collection of 27 sightings in movies, TV, culture and art {{DEFAULTSORT:27 (Number) Integers