Q: Is 421,643 a Prime Number?
A: Yes, 421,643 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 421643 can be evenly divided by 1 and 421,643, with no remainder.
Since 421,643 can be divided by just 1 and 421,643, it is a prime number.