A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2648880 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 13 15 16 18 20 24 26 30 36 39 40 45 48 52 60 65 72 78 80 90 104 117 120 130 144 156 180 195 208 234 240 260 283 312 360 390 468 520 566 585 624 720 780 849 936 1,040 1,132 1,170 1,415 1,560 1,698 1,872 2,264 2,340 2,547 2,830 3,120 3,396 3,679 4,245 4,528 4,680 5,094 5,660 6,792 7,358 8,490 9,360 10,188 11,037 11,320 12,735 13,584 14,716 16,980 18,395 20,376 22,074 22,640 25,470 29,432 33,111 33,960 36,790 40,752 44,148 50,940 55,185 58,864 66,222 67,920 73,580 88,296 101,880 110,370 132,444 147,160 165,555 176,592 203,760 220,740 264,888 294,320 331,110 441,480 529,776 662,220 882,960 1,324,440 and 2,648,880, with no remainder.
Since 2,648,880 cannot be divided by just 1 and 2,648,880, it is not a prime number.