A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5916680 can be evenly divided by 1 2 4 5 7 8 10 11 14 17 20 22 28 34 35 40 44 55 56 68 70 77 85 88 110 113 119 136 140 154 170 187 220 226 238 280 308 340 374 385 440 452 476 565 595 616 680 748 770 791 904 935 952 1,130 1,190 1,243 1,309 1,496 1,540 1,582 1,870 1,921 2,260 2,380 2,486 2,618 3,080 3,164 3,740 3,842 3,955 4,520 4,760 4,972 5,236 6,215 6,328 6,545 7,480 7,684 7,910 8,701 9,605 9,944 10,472 12,430 13,090 13,447 15,368 15,820 17,402 19,210 21,131 24,860 26,180 26,894 31,640 34,804 38,420 42,262 43,505 49,720 52,360 53,788 67,235 69,608 76,840 84,524 87,010 105,655 107,576 134,470 147,917 169,048 174,020 211,310 268,940 295,834 348,040 422,620 537,880 591,668 739,585 845,240 1,183,336 1,479,170 2,958,340 and 5,916,680, with no remainder.
Since 5,916,680 cannot be divided by just 1 and 5,916,680, it is not a prime number.