Q: Is 21,543 a Prime Number?
A: No, 21,543 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 21543 can be evenly divided by 1 3 43 129 167 501 7,181 and 21,543, with no remainder.
Since 21,543 cannot be divided by just 1 and 21,543, it is not a prime number.