Numbers / 820

The Number 820

820 is composite: factorization 2^2 × 5 × 41. That gives 820 exactly 12 divisors: 1, 2, 4, 5, 10, 20, 41, 82, 164, 205, 410, 820. 820's proper divisors total 944, 124 more than 820 itself, so 820 is abundant. 820 is also the 40th triangular number, the sum of 1 through 40. 820 has a digit sum of 10; for 820, the digital root works out to 1. 820: 2, 4, 5, 10 all divide 820 evenly, out of 2-12. 820 is 1100110100 in binary and 334 in hex; as a Roman numeral it's DCCCXX.