# 206 (number)

206 (two hundred [and] six) is the natural number following 205 and preceding 207.

 ← 205 206 207 →
Cardinaltwo hundred six
Ordinal206th
(two hundred sixth)
Factorization2 × 103
Divisors1, 2, 103, 206
Greek numeralΣϚ´
Roman numeralCCVI
Binary110011102
Ternary211223
Octal3168
Duodecimal15212

## In mathematics

206 is both a nontotient and a noncototient.[1] 206 is an untouchable number.[2] 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.[3] 206 and 207 form the second pair of consecutive numbers (after 14 and 15) whose sums of divisors are equal.[4] There are exactly 206 different linear forests on five labeled nodes,[5] and exactly 206 regular semigroups of order four up to isomorphism and anti-isomorphism.[6]

## In science

There are 206 bones in the typical adult human body.[7]

• Cessna 206, a single engine light aircraft
• Bell 206, a light helicopter
• The Peugeot 206, a French supermini automobile
• US Area code 206, 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, a novel by Kathy Reichs

## References

1. ^ Sloane, N. J. A. (ed.). "Sequence A058763 (Integers which are neither totient nor cototient)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
2. ^ "Sloane's A005114 : Untouchable numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. 2016-04-18. Retrieved 2016-04-18.
3. ^
4. ^
5. ^
6. ^
7. ^ O'Sullivan, Robyn (2006), Your 206 Bones, 32 Teeth, And Other Body Math, National Geographic Science Chapters, National Geographic Books, ISBN 9780792259558.