109 (number)

From Wikipedia, the free encyclopedia
← 108 109 110 →
← 100 101 102 103 104 105 106 107 108 109 →
List of numbers — Integers
← 0 100 200 300 400 500 600 700 800 900 →
Cardinalone hundred nine
Ordinal109th
(one hundred ninth)
Factorizationprime
Prime29th
Divisors1, 109
Greek numeralΡΘ´
Roman numeralCIX
Binary11011012
Ternary110013
Octal1558
Duodecimal9112
Hexadecimal6D16

109 (one hundred [and] nine) is the natural number following 108 and preceding 110.

In mathematics[]

109 is the 29th prime number, so it is a prime with a prime subscript.[1] The previous prime is 107, making them both twin primes.[2] 109 is a centered triangular number.[3]

There are exactly 109 different families of subsets of a three-element set whose union includes all three elements,[4] 109 different loops (invertible but not necessarily associative binary operations with an identity) on six elements, [5] and 109 squares on an infinite chessboard that can be reached by a knight within three moves.[6]

In other fields[]

  • 109 is also the atomic number of meitnerium.[7]
  • The diameter of the sun is about 109.1 to 109.5 the diameter of the earth.

See also[]

References[]

  1. ^ Sloane, N. J. A. (ed.). "Sequence A006450 (Primes with prime subscripts)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. ^ Sloane, N. J. A. (ed.). "Sequence A006512 (Greater of twin primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  3. ^ Sloane, N. J. A. (ed.). "Sequence A005448 (Centered triangular numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  4. ^ Sloane, N. J. A. (ed.). "Sequence A003465 (Number of ways to cover an n-set)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  5. ^ Sloane, N. J. A. (ed.). "Sequence A057771 (Number of loops (quasigroups with an identity element) of order n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  6. ^ Sloane, N. J. A. (ed.). "Sequence A018836 (Number of squares on infinite chess-board at ≤ n knight's moves from a fixed square)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  7. ^ Emsley, John (2011), Nature's Building Blocks: An A-Z Guide to the Elements, Oxford University Press, p. 316, ISBN 9780199605637.


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