A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5078580 can be evenly divided by 1 2 3 4 5 6 10 12 13 15 17 20 26 30 34 39 51 52 60 65 68 78 85 102 130 156 170 195 204 221 255 260 340 383 390 442 510 663 766 780 884 1,020 1,105 1,149 1,326 1,532 1,915 2,210 2,298 2,652 3,315 3,830 4,420 4,596 4,979 5,745 6,511 6,630 7,660 9,958 11,490 13,022 13,260 14,937 19,533 19,916 22,980 24,895 26,044 29,874 32,555 39,066 49,790 59,748 65,110 74,685 78,132 84,643 97,665 99,580 130,220 149,370 169,286 195,330 253,929 298,740 338,572 390,660 423,215 507,858 846,430 1,015,716 1,269,645 1,692,860 2,539,290 and 5,078,580, with no remainder.
Since 5,078,580 cannot be divided by just 1 and 5,078,580, it is not a prime number.