A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2918160 can be evenly divided by 1 2 3 4 5 6 7 8 9 10 12 14 15 16 18 20 21 24 27 28 30 35 36 40 42 45 48 54 56 60 63 70 72 80 84 90 105 108 112 120 126 135 140 144 168 180 189 193 210 216 240 252 270 280 315 336 360 378 386 420 432 504 540 560 579 630 720 756 772 840 945 965 1,008 1,080 1,158 1,260 1,351 1,512 1,544 1,680 1,737 1,890 1,930 2,160 2,316 2,520 2,702 2,895 3,024 3,088 3,474 3,780 3,860 4,053 4,632 5,040 5,211 5,404 5,790 6,755 6,948 7,560 7,720 8,106 8,685 9,264 10,422 10,808 11,580 12,159 13,510 13,896 15,120 15,440 16,212 17,370 20,265 20,844 21,616 23,160 24,318 26,055 27,020 27,792 32,424 34,740 36,477 40,530 41,688 46,320 48,636 52,110 54,040 60,795 64,848 69,480 72,954 81,060 83,376 97,272 104,220 108,080 121,590 138,960 145,908 162,120 182,385 194,544 208,440 243,180 291,816 324,240 364,770 416,880 486,360 583,632 729,540 972,720 1,459,080 and 2,918,160, with no remainder.
Since 2,918,160 cannot be divided by just 1 and 2,918,160, it is not a prime number.