Q: Is 668,640 a Prime Number?
A: No, 668,640 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 668640 can be evenly divided by 1 2 3 4 5 6 7 8 10 12 14 15 16 20 21 24 28 30 32 35 40 42 48 56 60 70 80 84 96 105 112 120 140 160 168 199 210 224 240 280 336 398 420 480 560 597 672 796 840 995 1,120 1,194 1,393 1,592 1,680 1,990 2,388 2,786 2,985 3,184 3,360 3,980 4,179 4,776 5,572 5,970 6,368 6,965 7,960 8,358 9,552 11,144 11,940 13,930 15,920 16,716 19,104 20,895 22,288 23,880 27,860 31,840 33,432 41,790 44,576 47,760 55,720 66,864 83,580 95,520 111,440 133,728 167,160 222,880 334,320 and 668,640, with no remainder.
Since 668,640 cannot be divided by just 1 and 668,640, it is not a prime number.