Numbers / 253

The Number 253

253 is composite: factorization 11 × 23. That gives 253 exactly 4 divisors: 1, 11, 23, 253. 253's proper divisors total just 35, 218 short of 253, the deficient case most of 253's neighbors share too. 253 is also the 22nd triangular number, the sum of 1 through 22. 253 has a digit sum of 10; for 253, the digital root works out to 1. 253: 11 all divide 253 evenly, out of 2-12. 253 is 11111101 in binary and FD in hex; as a Roman numeral it's CCLIII.