A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2656200 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 19 20 24 25 30 38 40 50 57 60 75 76 95 100 114 120 150 152 190 200 228 233 285 300 380 456 466 475 570 600 699 760 932 950 1,140 1,165 1,398 1,425 1,864 1,900 2,280 2,330 2,796 2,850 3,495 3,800 4,427 4,660 5,592 5,700 5,825 6,990 8,854 9,320 11,400 11,650 13,281 13,980 17,475 17,708 22,135 23,300 26,562 27,960 34,950 35,416 44,270 46,600 53,124 66,405 69,900 88,540 106,248 110,675 132,810 139,800 177,080 221,350 265,620 332,025 442,700 531,240 664,050 885,400 1,328,100 and 2,656,200, with no remainder.
Since 2,656,200 cannot be divided by just 1 and 2,656,200, it is not a prime number.