215 (two hundred
ndfifteen) is the
natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''Cardinal n ...
following
214 and preceding
216
__NOTOC__
Year 216 (Roman numerals, CCXVI) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Sabinus and Anullinus (or, less frequently, ...
.
In mathematics
*215 is a
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, ...
and a
semiprime
In mathematics, a semiprime is a natural number that is the product of exactly two prime numbers. The two primes in the product may equal each other, so the semiprimes include the squares of prime numbers.
Because there are infinitely many prime nu ...
.
*
*215 is the second smallest integer (after 5) such that
is twice a square:
.
*215 is a vertically symmetric number on a calculator display .
*There are 215 sequences of four integers, counting re-arrangements as distinct, such that the sum of their reciprocals is 1.
These are
**24 arrangements of (2,3,7,42), (2,3,8,24), (2,3,9,18), (2,3,10,15), (2,4,5,20) and (2,4,6,12).
**12 arrangements of (3,3,4,12), (3,4,4,6), (2,3,12,12), (2,4,8,8) and (2,5,5,10).
**6 arrangements of (3,3,6,6).
**4 arrangements of (2,6,6,6).
**1 arrangement of (4,4,4,4).
In other fields
*
215 Oenone is a
main belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere.
...
.
*E215 is the
E number
E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...
of
Sodium ethyl para-hydroxybenzoate
Ethylparaben (ethyl ''para''-hydroxybenzoate) is the ethyl ester of ''p''-hydroxybenzoic acid. Its formula is HO-C6H4-CO-O-CH2CH3. It is a member of the class of compounds known as parabens.
It is used as an antifungal preservative. As a food ...
.
*There are several
highways numbered 215.
215 is also:
*The
Dewey Decimal Classification
The Dewey Decimal Classification (DDC), colloquially known as the Dewey Decimal System, is a proprietary library classification system which allows new books to be added to a library in their appropriate location based on subject.
Section 4.1 ...
for
Science and religion
The relationship between religion and science involves discussions that interconnect the study of the natural world, history, philosophy, and theology. Even though the ancient and medieval worlds did not have conceptions resembling the modern u ...
.
*The year AD
215
Year 215 ( CCXV) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Laetus and Sulla (or, less frequently, year 968 ''Ab urbe condita''). ...
or
215 BC
Fifteen or 15 may refer to:
*15 (number), the natural number following 14 and preceding 16
*one of the years 15 BC, AD 15, 1915, 2015
Music
*Fifteen (band), a punk rock band
Albums
* ''15'' (Buckcherry album), 2005
* ''15'' (Ani Lorak album ...
*215 is often used as slang for
marijuana
Cannabis, also known as marijuana among other names, is a psychoactive drug from the cannabis plant. Native to Central or South Asia, the cannabis plant has been used as a drug for both recreational and entheogenic purposes and in various tra ...
, from
California Proposition 215, legalizing it for
medical use.
*The first
area code
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, rea ...
of metropolitan
Philadelphia, Pennsylvania
Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...
References
Integers
{{Num-stub
ca:Nombre 210#Nombres del 211 al 219