Q: Is 643,609 a Prime Number?
A: No, 643,609 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 643609 can be evenly divided by 1 23 27,983 and 643,609, with no remainder.
Since 643,609 cannot be divided by just 1 and 643,609, it is not a prime number.