Q: Is 555,991 a Prime Number?
A: No, 555,991 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 555991 can be evenly divided by 1 613 907 and 555,991, with no remainder.
Since 555,991 cannot be divided by just 1 and 555,991, it is not a prime number.