23 (number)

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

List of numbers — Integers << 20 21 22 23 24 25 26 27 28 29 >>
Cardinal	twenty-three
Ordinal	twenty-third
Factorization	prime
Roman numeral	XXIII
Binary	10111
Hexadecimal	17

In mathematics

Twenty-three is the ninth prime number, the sequence continues 29, 31, 37, 41,... Twenty-three is also a factorial prime, a Sophie Germain prime, a Woodall prime, and a Smarandache-Wellin prime.

23 also has the distinction of being one of two integers that can't be expressed as the sum of 8 cubes (we allow 0^3 since zero is indeed an integer). The other integer is 239.

23 is a Wedderburn-Etherington number.

In other fields

The 23rd moon of Jupiter is Carme.

Twenty-three is:

• The atomic number of vanadium.
• In early 20th century United States slang, it meant to leave a place. (From the phrase twenty-three skiddoo, which was a reference to Charles Dickens' novel A Tale of Two Cities, in which the hero Sydney Carlton was the twenty-third victim of the guillotine that day).
• The sacred number (along with 17 and 5) of Eris, Goddess of Discord from the Principia Discordia; it is the number of the Illuminati.
• Like 13, sometimes considered unlucky or otherwise significant (as in the occult writings of Aleister Crowley and William S. Burroughs).
• 23, a German movie about Karl Koch.
• A telegraphers' code meaning "line break".
• Michael Jordan's jersey number when he played for the Chicago Bulls
• When mathematician John Forbes Nash suffered from schizophrenic delusions, he said that Life Magazine had run a cover story of him disguised as Pope John XXIII as his name was John and his favorite prime number was 23.

• Historical years: 23 A.D., 23 B.C., or 1923