Q: Is 21,240 a Prime Number?
A: No, 21,240 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 21240 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 30 36 40 45 59 60 72 90 118 120 177 180 236 295 354 360 472 531 590 708 885 1,062 1,180 1,416 1,770 2,124 2,360 2,655 3,540 4,248 5,310 7,080 10,620 and 21,240, with no remainder.
Since 21,240 cannot be divided by just 1 and 21,240, it is not a prime number.