The prime factorization of 20 is: 2 x 2 x 5
?
2x2x5x5x23
100=2x2x5x5
2 x 19 = 38
24 x 3 x 17
It is: 2 to the power of 12 = 4096
847 = 7 x 11 x 11
2655 = 32 x 5 x 51
750 = 2 x 3 x 5 x 5 x 5
2 x 2 x 2 x 3 x 3 = 72
No, 20 isn't prime.
The first prime after 20 is 23.