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 ...
nontotient
In number theory, a nontotient is a positive integer ''n'' which is not a totient number: it is not in the range of Euler's totient function φ, that is, the equation φ(''x'') = ''n'' has no solution ''x''. In other words, ''n'' is a nontotien ...
and a
noncototient In mathematics, a noncototient is a positive integer ''n'' that cannot be expressed as the difference between a positive integer ''m'' and the number of coprime integers below it. That is, ''m'' − φ(''m'') = ''n'', where Ï ...
. 206 is an
untouchable number
An untouchable number is a positive integer that cannot be expressed as the sum of all the proper divisors of any positive integer (including the untouchable number itself). That is, these numbers are not in the image of the aliquot sum function. ...
. It is the lowest positive integer (when written in English as "two hundred and six") to employ all of the vowels once only, not including Y. The other numbers sharing this property are 230, 250, 260, 602, 640, 5000, 8000, 9000, 80,000 and 90,000. 206 and 207 form the second pair of consecutive numbers (after 14 and 15) whose sums of divisors are equal. There are exactly 206 different linear forests on five labeled nodes, and exactly 206
regular semigroup In mathematics, a regular semigroup is a semigroup ''S'' in which every element is regular, i.e., for each element ''a'' in ''S'' there exists an element ''x'' in ''S'' such that . Regular semigroups are one of the most-studied classes of semigroup ...
s of order four up to isomorphism and anti-isomorphism.
In science
There are 206 bones in the typical adult human body..
Peugeot 206
The Peugeot 206 is a supermini car ( B-segment) designed and produced by the French car manufacturer Peugeot since May 1998 as a replacement to the Peugeot 205. Developed under the codename ''T1'', it was released in September 1998 in hatchback ...
, a French supermini automobile
* US
Area code 206
Area code 206 is a North American telephone area code in the U.S. state of Washington serving Seattle and most of its innermost suburbs. The numbering plan area (NPA) includes such suburbs as Shoreline, Lake Forest Park, the islands of Mercer ...
, and The 206 slang terminology for the urban part of the greater Seattle area
* 206 (Ulster) Battery Royal Artillery (Volunteers) "The Ulster Gunners", part of British Army's 105th Regiment Royal Artillery (Volunteers)
* 206 Hersilia, a fairly large Main belt asteroid
* ''
206 Bones
''206 Bones'' is the twelfth novel by Kathy Reichs starring forensic anthropologist Temperance Brennan.
Plot
The book opens with Brennan imprisoned in an enclosed space, unable to remember where she is and how she got there.Integers