A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2051100 can be evenly divided by 1 2 3 4 5 6 9 10 12 15 18 20 25 30 36 43 45 50 53 60 75 86 90 100 106 129 150 159 172 180 212 215 225 258 265 300 318 387 430 450 477 516 530 636 645 774 795 860 900 954 1,060 1,075 1,290 1,325 1,548 1,590 1,908 1,935 2,150 2,279 2,385 2,580 2,650 3,180 3,225 3,870 3,975 4,300 4,558 4,770 5,300 6,450 6,837 7,740 7,950 9,116 9,540 9,675 11,395 11,925 12,900 13,674 15,900 19,350 20,511 22,790 23,850 27,348 34,185 38,700 41,022 45,580 47,700 56,975 68,370 82,044 102,555 113,950 136,740 170,925 205,110 227,900 341,850 410,220 512,775 683,700 1,025,550 and 2,051,100, with no remainder.
Since 2,051,100 cannot be divided by just 1 and 2,051,100, it is not a prime number.