Twenty-three is the ninth prime number and the smallest odd prime that is not a twin prime. [1] It forms a cousin prime pair with 19 and a sexy prime pair with both 17 and 29. It is the largest member of the first prime sextuplet (7, 11, 13, 17, 19, 23). [2] Twenty-three is also the next to last member of the first Cunningham chain of the first kind (2, 5, 11, 23, 47). [3] It is the sum of the …

