Q: Is 1,621,638 a Prime Number?
A: No, 1,621,638 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 1621638 can be evenly divided by 1 2 3 6 9 18 23 46 69 138 207 414 3,917 7,834 11,751 23,502 35,253 70,506 90,091 180,182 270,273 540,546 810,819 and 1,621,638, with no remainder.
Since 1,621,638 cannot be divided by just 1 and 1,621,638, it is not a prime number.