Q: Is 621,640 a Prime Number?
A: No, 621,640 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 621640 can be evenly divided by 1 2 4 5 8 10 20 40 15,541 31,082 62,164 77,705 124,328 155,410 310,820 and 621,640, with no remainder.
Since 621,640 cannot be divided by just 1 and 621,640, it is not a prime number.