Q: Is 21,255 a Prime Number?
A: No, 21,255 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 21255 can be evenly divided by 1 3 5 13 15 39 65 109 195 327 545 1,417 1,635 4,251 7,085 and 21,255, with no remainder.
Since 21,255 cannot be divided by just 1 and 21,255, it is not a prime number.