Numbers / 23

The Number 23

23 is prime: only 1 and 23 divide it evenly; the next prime after 23 is 29. 23's proper divisors total just 1, 22 short of 23, the deficient case most of 23's neighbors share too. 23 has a digit sum of 5; for 23, the digital root works out to 5. 23 shares no factor with 2-12; 23's own divisors start beyond that range. 23 is 10111 in binary and 17 in hex; as a Roman numeral it's XXIII.