A number factored into primes a^m * b^n ..... has (m + 1) ( n + 1)... positive divisors
6! = 720
Factor into primes
36 * 20 =
9 * 4 * 4 * 5 =
3^2 * 2^2 * 2^2 * 5 =
3^2 + 2^4 * 5^1
The number of positive divisors =
(2 + 1) ( 4 + 1) (1 + 1 ) =
3 * 5 * 2 =
30 positive divisors