Why is 291 not a prime number

I don't know whether it is or isn't. I'll need to examine it.

If it has any other factors besides 1 and 291, then it's not a prime number.

The factors of 291 are 1, 3, 97, and 291.

It's not a prime, because it has two more factors in addition to 1 and 291.

They are 3 and 97.

291 is not a prime number because it has divisors other then 1 and itself:

291 can be divided by 3 and 97