A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5873868 can be evenly divided by 1 2 3 4 6 7 9 11 12 13 14 18 21 22 26 28 33 36 39 42 44 52 63 66 77 78 84 91 99 117 126 132 143 154 156 163 182 198 231 234 252 273 286 308 326 364 396 429 462 468 489 546 572 652 693 819 858 924 978 1,001 1,092 1,141 1,287 1,386 1,467 1,638 1,716 1,793 1,956 2,002 2,119 2,282 2,574 2,772 2,934 3,003 3,276 3,423 3,586 4,004 4,238 4,564 5,148 5,379 5,868 6,006 6,357 6,846 7,172 8,476 9,009 10,269 10,758 12,012 12,551 12,714 13,692 14,833 16,137 18,018 19,071 20,538 21,516 23,309 25,102 25,428 29,666 32,274 36,036 37,653 38,142 41,076 44,499 46,618 50,204 59,332 64,548 69,927 75,306 76,284 88,998 93,236 112,959 133,497 139,854 150,612 163,163 177,996 209,781 225,918 266,994 279,708 326,326 419,562 451,836 489,489 533,988 652,652 839,124 978,978 1,468,467 1,957,956 2,936,934 and 5,873,868, with no remainder.
Since 5,873,868 cannot be divided by just 1 and 5,873,868, it is not a prime number.