Q: Is 643,553 a Prime Number?
A: Yes, 643,553 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 643553 can be evenly divided by 1 and 643,553, with no remainder.
Since 643,553 can be divided by just 1 and 643,553, it is a prime number.