Q: Is 688,640 a Prime Number?
A: No, 688,640 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 688640 can be evenly divided by 1 2 4 5 8 10 16 20 32 40 64 80 128 160 256 269 320 512 538 640 1,076 1,280 1,345 2,152 2,560 2,690 4,304 5,380 8,608 10,760 17,216 21,520 34,432 43,040 68,864 86,080 137,728 172,160 344,320 and 688,640, with no remainder.
Since 688,640 cannot be divided by just 1 and 688,640, it is not a prime number.