A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4580856 can be evenly divided by 1 2 3 4 6 7 8 9 12 14 18 21 24 28 36 42 56 61 63 72 84 122 126 149 168 183 244 252 298 366 427 447 488 504 549 596 732 854 894 1,043 1,098 1,192 1,281 1,341 1,464 1,708 1,788 2,086 2,196 2,562 2,682 3,129 3,416 3,576 3,843 4,172 4,392 5,124 5,364 6,258 7,686 8,344 9,089 9,387 10,248 10,728 12,516 15,372 18,178 18,774 25,032 27,267 30,744 36,356 37,548 54,534 63,623 72,712 75,096 81,801 109,068 127,246 163,602 190,869 218,136 254,492 327,204 381,738 508,984 572,607 654,408 763,476 1,145,214 1,526,952 2,290,428 and 4,580,856, with no remainder.
Since 4,580,856 cannot be divided by just 1 and 4,580,856, it is not a prime number.