Q: Is 645,664 a Prime Number?
A: No, 645,664 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 645664 can be evenly divided by 1 2 4 8 16 32 20,177 40,354 80,708 161,416 322,832 and 645,664, with no remainder.
Since 645,664 cannot be divided by just 1 and 645,664, it is not a prime number.