Q: Is 642,638 a Prime Number?
A: No, 642,638 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 642638 can be evenly divided by 1 2 321,319 and 642,638, with no remainder.
Since 642,638 cannot be divided by just 1 and 642,638, it is not a prime number.