A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8461308 can be evenly divided by 1 2 3 4 6 12 17 19 34 37 38 51 57 59 68 74 76 102 111 114 118 148 177 204 222 228 236 323 354 444 629 646 703 708 969 1,003 1,121 1,258 1,292 1,406 1,887 1,938 2,006 2,109 2,183 2,242 2,516 2,812 3,009 3,363 3,774 3,876 4,012 4,218 4,366 4,484 6,018 6,549 6,726 7,548 8,436 8,732 11,951 12,036 13,098 13,452 19,057 23,902 26,196 35,853 37,111 38,114 41,477 47,804 57,171 71,706 74,222 76,228 82,954 111,333 114,342 124,431 143,412 148,444 165,908 222,666 228,684 248,862 445,332 497,724 705,109 1,410,218 2,115,327 2,820,436 4,230,654 and 8,461,308, with no remainder.
Since 8,461,308 cannot be divided by just 1 and 8,461,308, it is not a prime number.