A number between 0 and 20 that has exactly two factors is a Prime number. Prime numbers are natural numbers greater than 1 that can only be divided by 1 and themselves without leaving a remainder. An example of a prime number between 0 and 20 is 17, as it can only be divided by 1 and 17 evenly.
28
16 has five factors.
16
4 and 9
Take your pick out of: 23 29 31 37 41 43 and 47 because as prime numbers they have only two factors
28
All of them. 2 3 5 7 11 13 17 19 have only two factors.
2,3,5,7,11,13,17,19
20 and 28 both have six factors.
The factors of 16 are 1, 2, 4, 8, and 16.
Because they only have two factors, as do 17 and 19.
48
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.
2, 3, 5, 7, 11, 13, 17, 19