A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2100450 can be evenly divided by 1 2 3 5 6 10 11 15 19 22 25 30 33 38 50 55 57 66 67 75 95 110 114 134 150 165 190 201 209 275 285 330 335 402 418 475 550 570 627 670 737 825 950 1,005 1,045 1,254 1,273 1,425 1,474 1,650 1,675 2,010 2,090 2,211 2,546 2,850 3,135 3,350 3,685 3,819 4,422 5,025 5,225 6,270 6,365 7,370 7,638 10,050 10,450 11,055 12,730 14,003 15,675 18,425 19,095 22,110 28,006 31,350 31,825 36,850 38,190 42,009 55,275 63,650 70,015 84,018 95,475 110,550 140,030 190,950 210,045 350,075 420,090 700,150 1,050,225 and 2,100,450, with no remainder.
Since 2,100,450 cannot be divided by just 1 and 2,100,450, it is not a prime number.