Q: Is 161,721 a Prime Number?
A: No, 161,721 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 161721 can be evenly divided by 1 3 7 9 17 21 51 63 119 151 153 357 453 1,057 1,071 1,359 2,567 3,171 7,701 9,513 17,969 23,103 53,907 and 161,721, with no remainder.
Since 161,721 cannot be divided by just 1 and 161,721, it is not a prime number.