Q: Is 645,640 a Prime Number?
A: No, 645,640 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 645640 can be evenly divided by 1 2 4 5 8 10 20 40 16,141 32,282 64,564 80,705 129,128 161,410 322,820 and 645,640, with no remainder.
Since 645,640 cannot be divided by just 1 and 645,640, it is not a prime number.