# 109 (number)

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 ← 108 109 110 →
Cardinal one hundred and nine
Ordinal 109th
(one hundred and ninth)
Factorization prime
Prime 29th
Divisors 1, 109
Roman numeral CIX
Binary 11011012
Ternary 110013
Quaternary 12314
Quinary 4145
Senary 3016
Octal 1558
Duodecimal 9112
Hexadecimal 6D16
Vigesimal 5920
Base 36 3136

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]