Q: Is 638,721 a Prime Number?
A: No, 638,721 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 638721 can be evenly divided by 1 3 9 70,969 212,907 and 638,721, with no remainder.
Since 638,721 cannot be divided by just 1 and 638,721, it is not a prime number.