Q: Is 643,642 a Prime Number?
A: No, 643,642 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 643642 can be evenly divided by 1 2 321,821 and 643,642, with no remainder.
Since 643,642 cannot be divided by just 1 and 643,642, it is not a prime number.