206 (number)

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← 205 206 207 →
Cardinaltwo hundred six
Ordinal206th
(two hundred sixth)
Factorization2 × 103
Divisors1, 2, 103, 206
Greek numeralΣϚ´
Roman numeralCCVI
Binary110011102
Ternary211223
Quaternary30324
Quinary13115
Senary5426
Octal3168
Duodecimal15212
HexadecimalCE16
VigesimalA620
Base 365Q36

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

In mathematics[edit]

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) to employ all of the vowels once only. 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[edit]

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

See also[edit]

  • The Year 206 AD
  • 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[edit]

  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. ^ Sloane, N.J.A. (ed.). "Sequence A058180 (Numbers whose English names include all five vowels exactly once)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  4. ^ Sloane, N.J.A. (ed.). "Sequence A002961 (Numbers n such that n and n+1 have same sum of divisors)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  5. ^ Sloane, N.J.A. (ed.). "Sequence A011800 (Number of labeled forests of n nodes each component of which is a path)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  6. ^ Sloane, N.J.A. (ed.). "Sequence A001427 (Number of regular semigroups of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  7. ^ O'Sullivan, Robyn (2006), Your 206 Bones, 32 Teeth, And Other Body Math, National Geographic Science Chapters, National Geographic Books, ISBN 9780792259558.