A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7647156 can be evenly divided by 1 2 3 4 6 9 11 12 18 22 27 33 36 41 44 54 66 82 99 108 123 132 157 164 198 246 297 314 369 396 451 471 492 594 628 738 902 942 1,107 1,188 1,353 1,413 1,476 1,727 1,804 1,884 2,214 2,706 2,826 3,454 4,059 4,239 4,428 5,181 5,412 5,652 6,437 6,908 8,118 8,478 10,362 12,177 12,874 15,543 16,236 16,956 19,311 20,724 24,354 25,748 31,086 38,622 46,629 48,708 57,933 62,172 70,807 77,244 93,258 115,866 141,614 173,799 186,516 212,421 231,732 283,228 347,598 424,842 637,263 695,196 849,684 1,274,526 1,911,789 2,549,052 3,823,578 and 7,647,156, with no remainder.
Since 7,647,156 cannot be divided by just 1 and 7,647,156, it is not a prime number.