Numbers / 659

The Number 659

659 is prime: only 1 and 659 divide it evenly; the next prime after 659 is 661. 659's proper divisors total just 1, 658 short of 659, the deficient case most of 659's neighbors share too. 659 has a digit sum of 20; for 659, the digital root works out to 2. 659 shares no factor with 2-12; 659's own divisors start beyond that range. 659 is 1010010011 in binary and 293 in hex; as a Roman numeral it's DCLIX.