Q: Is 21,878 a Prime Number?
A: No, 21,878 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 21878 can be evenly divided by 1 2 10,939 and 21,878, with no remainder.
Since 21,878 cannot be divided by just 1 and 21,878, it is not a prime number.