Q: Is 21,280 a Prime Number?
A: No, 21,280 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 21280 can be evenly divided by 1 2 4 5 7 8 10 14 16 19 20 28 32 35 38 40 56 70 76 80 95 112 133 140 152 160 190 224 266 280 304 380 532 560 608 665 760 1,064 1,120 1,330 1,520 2,128 2,660 3,040 4,256 5,320 10,640 and 21,280, with no remainder.
Since 21,280 cannot be divided by just 1 and 21,280, it is not a prime number.