A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2188200 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 84 100 105 120 140 150 168 175 200 210 280 300 350 420 521 525 600 700 840 1,042 1,050 1,400 1,563 2,084 2,100 2,605 3,126 3,647 4,168 4,200 5,210 6,252 7,294 7,815 10,420 10,941 12,504 13,025 14,588 15,630 18,235 20,840 21,882 26,050 29,176 31,260 36,470 39,075 43,764 52,100 54,705 62,520 72,940 78,150 87,528 91,175 104,200 109,410 145,880 156,300 182,350 218,820 273,525 312,600 364,700 437,640 547,050 729,400 1,094,100 and 2,188,200, with no remainder.
Since 2,188,200 cannot be divided by just 1 and 2,188,200, it is not a prime number.