Q: Is 21,609 a Prime Number?
A: No, 21,609 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 21609 can be evenly divided by 1 3 7 9 21 49 63 147 343 441 1,029 2,401 3,087 7,203 and 21,609, with no remainder.
Since 21,609 cannot be divided by just 1 and 21,609, it is not a prime number.