Answer :
for a number to be a prime number, it should have only 2 factors (divisible by): 1 and itself.
221 can be divided by 1, 13, 17, and itself so it’s not a prime number
same with 391, it’s not a prime number because it’s divisible by 1, 17, 23, 391
221 can be divided by 1, 13, 17, and itself so it’s not a prime number
same with 391, it’s not a prime number because it’s divisible by 1, 17, 23, 391
