A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4626776 can be evenly divided by 1 2 4 7 8 11 14 22 28 29 37 44 49 56 58 74 77 88 98 116 148 154 196 203 232 259 296 308 319 392 406 407 518 539 616 638 812 814 1,036 1,073 1,078 1,276 1,421 1,624 1,628 1,813 2,072 2,146 2,156 2,233 2,552 2,842 2,849 3,256 3,626 4,292 4,312 4,466 5,684 5,698 7,252 7,511 8,584 8,932 11,368 11,396 11,803 14,504 15,022 15,631 17,864 19,943 22,792 23,606 30,044 31,262 39,886 47,212 52,577 60,088 62,524 79,772 82,621 94,424 105,154 125,048 159,544 165,242 210,308 330,484 420,616 578,347 660,968 1,156,694 2,313,388 and 4,626,776, with no remainder.
Since 4,626,776 cannot be divided by just 1 and 4,626,776, it is not a prime number.