23 (number)

From Freepedia

23 (twenty-three) is the natural number following 22 and preceding 24.

<< 20 21 22 23 24 25 26 27 28 29 >>

Cardinal twenty-three
Ordinaltwenty-third
Factorizationprime
Roman numeralXXIII
Binary10111
Octal27
Hexadecimal17

Contents

In mathematics

Twenty-three is the ninth prime number, the sequence continues 29, 31, 37, 41,... Twenty-three is also the fifth factorial prime, the fifth Sophie Germain prime, the fourth safe prime, the second Woodall prime, and the second Smarandache-Wellin prime. It is an Eisenstein prime with no imaginary part and real part of the form <math>3n - 1</math>.

23 also has the distinction of being one of two integers that cannot be expressed as the sum of fewer than 9 cubes of integers (the other is 239). See Waring's problem.

23 is a Wedderburn-Etherington number.

23 is a highly cototient number.

23 is the smallest odd prime that is not a twin prime.

23 is the size of the codewords in the perfect (non-extended) binary Golay code.

In science

In astronomy,

Messier object M23, a magnitude 6.0 open cluster in the constellation Sagittarius
The New General Catalogue object NGC 23, a magnitude 12.0 barred spiral galaxy in the constellation Pegasus
The Saros number of the solar eclipse series which began on -2145 May 7 and ended on -865 June 15. The duration of Saros series 23 was 1280.1 years, and it contained 72 solar eclipses.
The Saros number of the lunar eclipse series which began on -1843 February 14 and ended on -527 April 14. The duration of Saros series 23 was 1316.2 years, and it contained 74 lunar eclipses.
The 23rd moon of Jupiter is Carme

Occult significance


In other fields

Twenty-three is:



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