Q: Is 561 a Prime Number?
A: No, 561 is not a prime number.
A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 561 can be evenly divided by 1 3 11 17 33 51 187 and 561, with no remainder.
Since 561 cannot be divided by just 1 and 561, it is not a prime number.