Numbers / 171

The Number 171

171 is composite: factorization 3^2 × 19. That gives 171 exactly 6 divisors: 1, 3, 9, 19, 57, 171. 171's proper divisors total just 89, 82 short of 171, the deficient case most of 171's neighbors share too. 171 also carries: the 18th triangular number, the sum of 1 through 18; and a palindrome, since 171 reads identically forwards and backwards. 171 has a digit sum of 9; for 171, the digital root works out to 9. 171: 3, 9 all divide 171 evenly, out of 2-12. 171 is 10101011 in binary and AB in hex; as a Roman numeral it's CLXXI.