A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8516160 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 30 32 36 40 45 48 60 64 72 80 90 96 120 144 160 180 192 240 288 320 360 480 576 720 960 1,440 2,880 2,957 5,914 8,871 11,828 14,785 17,742 23,656 26,613 29,570 35,484 44,355 47,312 53,226 59,140 70,968 88,710 94,624 106,452 118,280 133,065 141,936 177,420 189,248 212,904 236,560 266,130 283,872 354,840 425,808 473,120 532,260 567,744 709,680 851,616 946,240 1,064,520 1,419,360 1,703,232 2,129,040 2,838,720 4,258,080 and 8,516,160, with no remainder.
Since 8,516,160 cannot be divided by just 1 and 8,516,160, it is not a prime number.