Numbers / 66

The Number 66

66 is composite: factorization 2 × 3 × 11. That gives 66 exactly 8 divisors: 1, 2, 3, 6, 11, 22, 33, 66. 66's proper divisors total 78, 12 more than 66 itself, so 66 is abundant. 66 also carries: the 11th triangular number, the sum of 1 through 11; and a palindrome, since 66 reads identically forwards and backwards. 66 has a digit sum of 12; for 66, the digital root works out to 3. 66: 2, 3, 6, 11 all divide 66 evenly, out of 2-12. 66 is 1000010 in binary and 42 in hex; as a Roman numeral it's LXVI.