1 and 3
Out of the list of factors of 36, 2 and 3 are the only prime numbers.
I really don't know
The factors of 6 are: 1, 2, 3, 6.
The factors of 867 are 1 3 17 51 289 867, and the prime factors are 3 and 172.
Because on the list of factors of 24, 2 and 3 are the only prime numbers.
That's an infinite list.
2 and 3
The factors of 63 are: 1, 3, 7, 9, 21, 63.
The factors for 6 are: 1,2,3,and 6
1, 3, 11, 33
3 and 5