23
Cardinal	twenty-three
Ordinal	Twenty-third
Factorization	(prime number)
Roman numeral	XXIII
Binary	10111
Hexadecimal	17

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

Twenty-three is:

• The atomic number of vanadium.
• In early 20th century United States slang, it meant to leave a place.
• The sacred number of Eris, Goddess of Discord? (along with 17 and 5) from Principia Discordia; it is the number of the Illuminati.
• 23, a movie by Karl Koch.
• The year AD 23.