A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3176280 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 90 102 108 120 135 136 153 170 173 180 204 216 255 270 306 340 346 360 408 459 510 519 540 612 680 692 765 865 918 1,020 1,038 1,080 1,224 1,384 1,530 1,557 1,730 1,836 2,040 2,076 2,295 2,595 2,941 3,060 3,114 3,460 3,672 4,152 4,590 4,671 5,190 5,882 6,120 6,228 6,920 7,785 8,823 9,180 9,342 10,380 11,764 12,456 14,705 15,570 17,646 18,360 18,684 20,760 23,355 23,528 26,469 29,410 31,140 35,292 37,368 44,115 46,710 52,938 58,820 62,280 70,584 79,407 88,230 93,420 105,876 117,640 132,345 158,814 176,460 186,840 211,752 264,690 317,628 352,920 397,035 529,380 635,256 794,070 1,058,760 1,588,140 and 3,176,280, with no remainder.
Since 3,176,280 cannot be divided by just 1 and 3,176,280, it is not a prime number.