1, 3, 9, 13, 39, 117
13 if you include the '75', 12 if you don't.
3 numbers are factors of 121. They are 1, 11 and 121 itself.
There are 14C5 = 14*13*12*11*10/(5*4*3*2*1) = 2002
1, 2, 4, 7, 13, 14, 26, 28, 52, 91, 182 and 364.
There are infinitely many such numbers.
Only itself and one because 13 is a prime number
Four: 1 2 13 26.
1 and 13.
Four: 1, 2, 13, 26.
1, 2, 4, 13, 26, 52.
There are an infinite amount of prime numbers. Starting with 2, 3, 5, 7, 11, 13, 17 ... the numbers, as all numbers go to infinity.
1 and 13.
There are an infinite amount of prime numbers. Starting with 2, 3, 5, 7, 11, 13, 17 ... the numbers, as all numbers go to infinity.
1 and 13. 13 is a prime number, thus only 1 and itself can go into it.
26
Only 1 and 13, it's a prime.