Q: Is 685,640 a Prime Number?
A: No, 685,640 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 685640 can be evenly divided by 1 2 4 5 8 10 20 40 61 122 244 281 305 488 562 610 1,124 1,220 1,405 2,248 2,440 2,810 5,620 11,240 17,141 34,282 68,564 85,705 137,128 171,410 342,820 and 685,640, with no remainder.
Since 685,640 cannot be divided by just 1 and 685,640, it is not a prime number.