Q: Is 643,840 a Prime Number?
A: No, 643,840 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 643840 can be evenly divided by 1 2 4 5 8 10 16 20 32 40 64 80 128 160 256 320 503 640 1,006 1,280 2,012 2,515 4,024 5,030 8,048 10,060 16,096 20,120 32,192 40,240 64,384 80,480 128,768 160,960 321,920 and 643,840, with no remainder.
Since 643,840 cannot be divided by just 1 and 643,840, it is not a prime number.