Numbers / 621

The Number 621

621 is composite: factorization 3^3 × 23. That gives 621 exactly 8 divisors: 1, 3, 9, 23, 27, 69, 207, 621. 621's proper divisors total just 339, 282 short of 621, the deficient case most of 621's neighbors share too. 621 has a digit sum of 9; for 621, the digital root works out to 9. 621: 3, 9 all divide 621 evenly, out of 2-12. 621 is 1001101101 in binary and 26D in hex; as a Roman numeral it's DCXXI.