Q: Is 21,508 a Prime Number?
A: No, 21,508 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 21508 can be evenly divided by 1 2 4 19 38 76 283 566 1,132 5,377 10,754 and 21,508, with no remainder.
Since 21,508 cannot be divided by just 1 and 21,508, it is not a prime number.