Numbers / 664

The Number 664

664 is composite: factorization 2^3 × 83. That gives 664 exactly 8 divisors: 1, 2, 4, 8, 83, 166, 332, 664. 664's proper divisors total just 596, 68 short of 664, the deficient case most of 664's neighbors share too. 664 has a digit sum of 16; for 664, the digital root works out to 7. 664: 2, 4, 8 all divide 664 evenly, out of 2-12. 664 is 1010011000 in binary and 298 in hex; as a Roman numeral it's DCLXIV.