A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5515320 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 19 20 24 30 38 40 41 57 59 60 76 82 95 114 118 120 123 152 164 177 190 205 228 236 246 285 295 328 354 380 410 456 472 492 570 590 615 708 760 779 820 885 984 1,121 1,140 1,180 1,230 1,416 1,558 1,640 1,770 2,242 2,280 2,337 2,360 2,419 2,460 3,116 3,363 3,540 3,895 4,484 4,674 4,838 4,920 5,605 6,232 6,726 7,080 7,257 7,790 8,968 9,348 9,676 11,210 11,685 12,095 13,452 14,514 15,580 16,815 18,696 19,352 22,420 23,370 24,190 26,904 29,028 31,160 33,630 36,285 44,840 45,961 46,740 48,380 58,056 67,260 72,570 91,922 93,480 96,760 134,520 137,883 145,140 183,844 229,805 275,766 290,280 367,688 459,610 551,532 689,415 919,220 1,103,064 1,378,830 1,838,440 2,757,660 and 5,515,320, with no remainder.
Since 5,515,320 cannot be divided by just 1 and 5,515,320, it is not a prime number.