Q: Is 21,420 a Composite Number?
A: Yes, 21,420 is a composite number.
The number 21,420 can be evenly divided by 1 2 3 4 5 6 7 9 10 12 14 15 17 18 20 21 28 30 34 35 36 42 45 51 60 63 68 70 84 85 90 102 105 119 126 140 153 170 180 204 210 238 252 255 306 315 340 357 420 476 510 595 612 630 714 765 1,020 1,071 1,190 1,260 1,428 1,530 1,785 2,142 2,380 3,060 3,570 4,284 5,355 7,140 10,710 and 21,420, with no remainder.
Since 21,420 cannot be divided by just 1 and 21,420, it is a composite number.