This site addresses the problem.
Write the number as the product of prime factors, each with the appropriate exponent. The total number of divisors is the product of the numbers you get when you add 1 to each of the exponents.
Example:
180 = 22*32*5
The exponents of the factors are 2, 2, and 1, respectively. The total number of divisors of 180 is (2+1)(2+1)(1+1) = 3*3*2 = 18
They are
1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 60, 90, 180
Write the number as the product of prime factors, each with the appropriate exponent. The total number of divisors is the product of the numbers you get when you add 1 to each of the exponents.
Example:
180 = 22*32*5
The exponents of the factors are 2, 2, and 1, respectively. The total number of divisors of 180 is (2+1)(2+1)(1+1) = 3*3*2 = 18
They are
1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 60, 90, 180
