Q: Is 640,605 a Prime Number?
A: No, 640,605 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 640605 can be evenly divided by 1 3 5 7 15 21 35 105 6,101 18,303 30,505 42,707 91,515 128,121 213,535 and 640,605, with no remainder.
Since 640,605 cannot be divided by just 1 and 640,605, it is not a prime number.