Numbers / 640

The Number 640

640 is composite: factorization 2^7 × 5. That gives 640 exactly 16 divisors: 1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 128, 160, 320, 640. 640's proper divisors total 890, 250 more than 640 itself, so 640 is abundant. 640 has a digit sum of 10; for 640, the digital root works out to 1. 640: 2, 4, 5, 8, 10 all divide 640 evenly, out of 2-12. 640 is 1010000000 in binary and 280 in hex; as a Roman numeral it's DCXL.