Numbers / 43

The Number 43

43 is prime: only 1 and 43 divide it evenly; the next prime after 43 is 47. 43's proper divisors total just 1, 42 short of 43, the deficient case most of 43's neighbors share too. 43 has a digit sum of 7; for 43, the digital root works out to 7. 43 shares no factor with 2-12; 43's own divisors start beyond that range. 43 is 101011 in binary and 2B in hex; as a Roman numeral it's XLIII.