Q: Is 21,000 a Prime Number?
A: No, 21,000 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 21000 can be evenly divided by 1 2 3 4 5 6 7 8 10 12 14 15 20 21 24 25 28 30 35 40 42 50 56 60 70 75 84 100 105 120 125 140 150 168 175 200 210 250 280 300 350 375 420 500 525 600 700 750 840 875 1,000 1,050 1,400 1,500 1,750 2,100 2,625 3,000 3,500 4,200 5,250 7,000 10,500 and 21,000, with no remainder.
Since 21,000 cannot be divided by just 1 and 21,000, it is not a prime number.