Numbers / 121

The Number 121

121 is composite: factorization 11^2. That gives 121 exactly 3 divisors: 1, 11, 121. 121's proper divisors total just 12, 109 short of 121, the deficient case most of 121's neighbors share too. 121 also carries: a perfect square, since 11² = 121; and a palindrome, since 121 reads identically forwards and backwards. 121 has a digit sum of 4; for 121, the digital root works out to 4. 121: 11 all divide 121 evenly, out of 2-12. 121 is 1111001 in binary and 79 in hex; as a Roman numeral it's CXXI.