Q: Is 21,861 a Prime Number?
A: No, 21,861 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 21861 can be evenly divided by 1 3 7 9 21 63 347 1,041 2,429 3,123 7,287 and 21,861, with no remainder.
Since 21,861 cannot be divided by just 1 and 21,861, it is not a prime number.