Q: Is 643,000 a Prime Number?
A: No, 643,000 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 643000 can be evenly divided by 1 2 4 5 8 10 20 25 40 50 100 125 200 250 500 643 1,000 1,286 2,572 3,215 5,144 6,430 12,860 16,075 25,720 32,150 64,300 80,375 128,600 160,750 321,500 and 643,000, with no remainder.
Since 643,000 cannot be divided by just 1 and 643,000, it is not a prime number.