Q: Is 21,640 a Prime Number?
A: No, 21,640 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 21640 can be evenly divided by 1 2 4 5 8 10 20 40 541 1,082 2,164 2,705 4,328 5,410 10,820 and 21,640, with no remainder.
Since 21,640 cannot be divided by just 1 and 21,640, it is not a prime number.