Numbers / 289

The Number 289

289 is composite: factorization 17^2. That gives 289 exactly 3 divisors: 1, 17, 289. 289's proper divisors total just 18, 271 short of 289, the deficient case most of 289's neighbors share too. 289 is also a perfect square, since 17² = 289. 289 has a digit sum of 19; for 289, the digital root works out to 1. 289 shares no factor with 2-12; 289's own divisors start beyond that range. 289 is 100100001 in binary and 121 in hex; as a Roman numeral it's CCLXXXIX.