Q: Is 21,615 a Prime Number?
A: No, 21,615 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 21615 can be evenly divided by 1 3 5 11 15 33 55 131 165 393 655 1,441 1,965 4,323 7,205 and 21,615, with no remainder.
Since 21,615 cannot be divided by just 1 and 21,615, it is not a prime number.