A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8514240 can be evenly divided by 1 2 3 4 5 6 7 8 10 12 14 15 16 20 21 24 28 30 32 35 40 42 48 49 56 60 64 70 80 84 96 98 105 112 120 140 147 160 168 181 192 196 210 224 240 245 280 294 320 336 362 392 420 448 480 490 543 560 588 672 724 735 784 840 905 960 980 1,086 1,120 1,176 1,267 1,344 1,448 1,470 1,568 1,680 1,810 1,960 2,172 2,240 2,352 2,534 2,715 2,896 2,940 3,136 3,360 3,620 3,801 3,920 4,344 4,704 5,068 5,430 5,792 5,880 6,335 6,720 7,240 7,602 7,840 8,688 8,869 9,408 10,136 10,860 11,584 11,760 12,670 14,480 15,204 15,680 17,376 17,738 19,005 20,272 21,720 23,520 25,340 26,607 28,960 30,408 34,752 35,476 38,010 40,544 43,440 44,345 47,040 50,680 53,214 57,920 60,816 70,952 76,020 81,088 86,880 88,690 101,360 106,428 121,632 133,035 141,904 152,040 173,760 177,380 202,720 212,856 243,264 266,070 283,808 304,080 354,760 405,440 425,712 532,140 567,616 608,160 709,520 851,424 1,064,280 1,216,320 1,419,040 1,702,848 2,128,560 2,838,080 4,257,120 and 8,514,240, with no remainder.
Since 8,514,240 cannot be divided by just 1 and 8,514,240, it is not a prime number.