Q: Is 643,998 a Prime Number?
A: No, 643,998 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 643998 can be evenly divided by 1 2 3 6 181 362 543 593 1,086 1,186 1,779 3,558 107,333 214,666 321,999 and 643,998, with no remainder.
Since 643,998 cannot be divided by just 1 and 643,998, it is not a prime number.