Numbers / 668

The Number 668

668 is composite: factorization 2^2 × 167. That gives 668 exactly 6 divisors: 1, 2, 4, 167, 334, 668. 668's proper divisors total just 508, 160 short of 668, the deficient case most of 668's neighbors share too. 668 has a digit sum of 20; for 668, the digital root works out to 2. 668: 2, 4 all divide 668 evenly, out of 2-12. 668 is 1010011100 in binary and 29C in hex; as a Roman numeral it's DCLXVIII.