A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6264720 can be evenly divided by 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 18 20 21 22 24 28 30 33 35 36 40 42 44 45 48 55 56 60 63 66 70 72 77 80 84 88 90 99 105 110 112 113 120 126 132 140 144 154 165 168 176 180 198 210 220 226 231 240 252 264 280 308 315 330 336 339 360 385 396 420 440 452 462 495 504 528 560 565 616 630 660 678 693 720 770 791 792 840 880 904 924 990 1,008 1,017 1,130 1,155 1,232 1,243 1,260 1,320 1,356 1,386 1,540 1,582 1,584 1,680 1,695 1,808 1,848 1,980 2,034 2,260 2,310 2,373 2,486 2,520 2,640 2,712 2,772 3,080 3,164 3,390 3,465 3,696 3,729 3,955 3,960 4,068 4,520 4,620 4,746 4,972 5,040 5,085 5,424 5,544 6,160 6,215 6,328 6,780 6,930 7,119 7,458 7,910 7,920 8,136 8,701 9,040 9,240 9,492 9,944 10,170 11,088 11,187 11,865 12,430 12,656 13,560 13,860 14,238 14,916 15,820 16,272 17,402 18,480 18,645 18,984 19,888 20,340 22,374 23,730 24,860 26,103 27,120 27,720 28,476 29,832 31,640 34,804 35,595 37,290 37,968 40,680 43,505 44,748 47,460 49,720 52,206 55,440 55,935 56,952 59,664 63,280 69,608 71,190 74,580 78,309 81,360 87,010 89,496 94,920 99,440 104,412 111,870 113,904 130,515 139,216 142,380 149,160 156,618 174,020 178,992 189,840 208,824 223,740 261,030 284,760 298,320 313,236 348,040 391,545 417,648 447,480 522,060 569,520 626,472 696,080 783,090 894,960 1,044,120 1,252,944 1,566,180 2,088,240 3,132,360 and 6,264,720, with no remainder.
Since 6,264,720 cannot be divided by just 1 and 6,264,720, it is not a prime number.