16
The factors of 16 are 1, 2, 4, 8, and 16.
12, 18 and 20 each have six factors.
For a number to have [only] 2 factors, it must be a prime number; the prime numbers between 0 and 20 are; 2, 3, 5, 7, 11, 13, 17, 19
240 has 20 factors.
16
16
16
16
48
48
20 and 28 both have six factors.
The factors of 16 are 1, 2, 4, 8, and 16.
12, 18 and 20 each have six factors.
16 has five factors.
16 has five factors.
5, 10, 15 and 20 have five as a factor. The number 16 has five factors.