Q: Is 21,855 a Prime Number?
A: No, 21,855 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 21855 can be evenly divided by 1 3 5 15 31 47 93 141 155 235 465 705 1,457 4,371 7,285 and 21,855, with no remainder.
Since 21,855 cannot be divided by just 1 and 21,855, it is not a prime number.