Q: Is 21,729 a Prime Number?
A: No, 21,729 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 21729 can be evenly divided by 1 3 7,243 and 21,729, with no remainder.
Since 21,729 cannot be divided by just 1 and 21,729, it is not a prime number.