Q: Is 687,721 a Prime Number?
A: Yes, 687,721 is a prime number.
A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 687721 can be evenly divided by 1 and 687,721, with no remainder.
Since 687,721 can be divided by just 1 and 687,721, it is a prime number.