Q: Is 21,788 a Prime Number?
A: No, 21,788 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 21788 can be evenly divided by 1 2 4 13 26 52 419 838 1,676 5,447 10,894 and 21,788, with no remainder.
Since 21,788 cannot be divided by just 1 and 21,788, it is not a prime number.