Q: Is 21,511 a Prime Number?
A: No, 21,511 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 21511 can be evenly divided by 1 7 49 439 3,073 and 21,511, with no remainder.
Since 21,511 cannot be divided by just 1 and 21,511, it is not a prime number.