A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1183680 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 27 30 32 36 40 45 48 54 60 64 72 80 90 96 108 120 135 137 144 160 180 192 216 240 270 274 288 320 360 411 432 480 540 548 576 685 720 822 864 960 1,080 1,096 1,233 1,370 1,440 1,644 1,728 2,055 2,160 2,192 2,466 2,740 2,880 3,288 3,699 4,110 4,320 4,384 4,932 5,480 6,165 6,576 7,398 8,220 8,640 8,768 9,864 10,960 12,330 13,152 14,796 16,440 18,495 19,728 21,920 24,660 26,304 29,592 32,880 36,990 39,456 43,840 49,320 59,184 65,760 73,980 78,912 98,640 118,368 131,520 147,960 197,280 236,736 295,920 394,560 591,840 and 1,183,680, with no remainder.
Since 1,183,680 cannot be divided by just 1 and 1,183,680, it is not a prime number.