A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8106624 can be evenly divided by 1 2 3 4 6 8 9 12 16 18 24 31 32 36 48 62 64 72 93 96 124 128 144 186 192 227 248 279 288 372 384 454 496 558 576 681 744 908 992 1,116 1,152 1,362 1,488 1,816 1,984 2,043 2,232 2,724 2,976 3,632 3,968 4,086 4,464 5,448 5,952 7,037 7,264 8,172 8,928 10,896 11,904 14,074 14,528 16,344 17,856 21,111 21,792 28,148 29,056 32,688 35,712 42,222 43,584 56,296 63,333 65,376 84,444 87,168 112,592 126,666 130,752 168,888 225,184 253,332 261,504 337,776 450,368 506,664 675,552 900,736 1,013,328 1,351,104 2,026,656 2,702,208 4,053,312 and 8,106,624, with no remainder.
Since 8,106,624 cannot be divided by just 1 and 8,106,624, it is not a prime number.