A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8248416 can be evenly divided by 1 2 3 4 6 8 11 12 16 22 24 32 33 44 48 66 73 88 96 107 132 146 176 214 219 264 292 321 352 428 438 528 584 642 803 856 876 1,056 1,168 1,177 1,284 1,606 1,712 1,752 2,336 2,354 2,409 2,568 3,212 3,424 3,504 3,531 4,708 4,818 5,136 6,424 7,008 7,062 7,811 9,416 9,636 10,272 12,848 14,124 15,622 18,832 19,272 23,433 25,696 28,248 31,244 37,664 38,544 46,866 56,496 62,488 77,088 85,921 93,732 112,992 124,976 171,842 187,464 249,952 257,763 343,684 374,928 515,526 687,368 749,856 1,031,052 1,374,736 2,062,104 2,749,472 4,124,208 and 8,248,416, with no remainder.
Since 8,248,416 cannot be divided by just 1 and 8,248,416, it is not a prime number.