Numbers / 663

The Number 663

663 is composite: factorization 3 × 13 × 17. That gives 663 exactly 8 divisors: 1, 3, 13, 17, 39, 51, 221, 663. 663's proper divisors total just 345, 318 short of 663, the deficient case most of 663's neighbors share too. 663 has a digit sum of 15; for 663, the digital root works out to 6. 663: 3 all divide 663 evenly, out of 2-12. 663 is 1010010111 in binary and 297 in hex; as a Roman numeral it's DCLXIII.