A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3186360 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 30 36 40 45 53 60 72 90 106 120 159 167 180 212 265 318 334 360 424 477 501 530 636 668 795 835 954 1,002 1,060 1,272 1,336 1,503 1,590 1,670 1,908 2,004 2,120 2,385 2,505 3,006 3,180 3,340 3,816 4,008 4,770 5,010 6,012 6,360 6,680 7,515 8,851 9,540 10,020 12,024 15,030 17,702 19,080 20,040 26,553 30,060 35,404 44,255 53,106 60,120 70,808 79,659 88,510 106,212 132,765 159,318 177,020 212,424 265,530 318,636 354,040 398,295 531,060 637,272 796,590 1,062,120 1,593,180 and 3,186,360, with no remainder.
Since 3,186,360 cannot be divided by just 1 and 3,186,360, it is not a prime number.