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31 (number)

From Wikipedia, the free encyclopedia
Natural number
← 3031 32 →
Cardinalthirty-one
Ordinal31st
(thirty-first)
Factorizationprime
Prime11th
Divisors1, 31
Greek numeralΛΑ´
Roman numeralXXXI,xxxi
Binary111112
Ternary10113
Senary516
Octal378
Duodecimal2712
Hexadecimal1F16

31 (thirty-one) is the natural number following30 and preceding32. It is a prime number.

Mathematics

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31 is aprime number, atwin prime[1] (with29), and aMersenne prime.[2]

31 is acentered pentagonal number.

In other fields

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31 equal temperament is a popularmicrotonal tuning for musical instruments because it provides a good approximation of harmonic intervals.

January,March,May,July,August,October andDecember have 31 days.

California was the 31st state to join theUnited States.

31 is the international calling code forthe Netherlands.

Notes

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References

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  1. ^Sloane, N. J. A. (ed.)."Sequence A077800 (List of twin primes {p, p+2}.)".TheOn-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved2023-06-07.
  2. ^Sloane, N. J. A. (ed.)."Sequence A000668 (Mersenne primes (primes of the form 2^n - 1).)".TheOn-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved2023-06-07.

External links

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Look upthirty-one in Wiktionary, the free dictionary.
Wikimedia Commons has media related to31 (number).
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