A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8463960 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 17 18 20 24 27 30 34 36 40 45 51 54 60 68 72 85 90 102 108 120 135 136 153 170 180 204 216 255 270 306 340 360 408 459 461 510 540 612 680 765 918 922 1,020 1,080 1,224 1,383 1,530 1,836 1,844 2,040 2,295 2,305 2,766 3,060 3,672 3,688 4,149 4,590 4,610 5,532 6,120 6,915 7,837 8,298 9,180 9,220 11,064 12,447 13,830 15,674 16,596 18,360 18,440 20,745 23,511 24,894 27,660 31,348 33,192 39,185 41,490 47,022 49,788 55,320 62,235 62,696 70,533 78,370 82,980 94,044 99,576 117,555 124,470 141,066 156,740 165,960 188,088 211,599 235,110 248,940 282,132 313,480 352,665 423,198 470,220 497,880 564,264 705,330 846,396 940,440 1,057,995 1,410,660 1,692,792 2,115,990 2,821,320 4,231,980 and 8,463,960, with no remainder.
Since 8,463,960 cannot be divided by just 1 and 8,463,960, it is not a prime number.