Numbers / 646

The Number 646

646 is composite: factorization 2 × 17 × 19. That gives 646 exactly 8 divisors: 1, 2, 17, 19, 34, 38, 323, 646. 646's proper divisors total just 434, 212 short of 646, the deficient case most of 646's neighbors share too. 646 is also a palindrome, since 646 reads identically forwards and backwards. 646 has a digit sum of 16; for 646, the digital root works out to 7. 646: 2 all divide 646 evenly, out of 2-12. 646 is 1010000110 in binary and 286 in hex; as a Roman numeral it's DCXLVI.