A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2106300 can be evenly divided by 1 2 3 4 5 6 7 10 12 14 15 17 20 21 25 28 30 34 35 42 50 51 59 60 68 70 75 84 85 100 102 105 118 119 140 150 170 175 177 204 210 236 238 255 295 300 340 350 354 357 413 420 425 476 510 525 590 595 700 708 714 826 850 885 1,003 1,020 1,050 1,180 1,190 1,239 1,275 1,428 1,475 1,652 1,700 1,770 1,785 2,006 2,065 2,100 2,380 2,478 2,550 2,950 2,975 3,009 3,540 3,570 4,012 4,130 4,425 4,956 5,015 5,100 5,900 5,950 6,018 6,195 7,021 7,140 8,260 8,850 8,925 10,030 10,325 11,900 12,036 12,390 14,042 15,045 17,700 17,850 20,060 20,650 21,063 24,780 25,075 28,084 30,090 30,975 35,105 35,700 41,300 42,126 50,150 60,180 61,950 70,210 75,225 84,252 100,300 105,315 123,900 140,420 150,450 175,525 210,630 300,900 351,050 421,260 526,575 702,100 1,053,150 and 2,106,300, with no remainder.
Since 2,106,300 cannot be divided by just 1 and 2,106,300, it is not a prime number.