A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 627264 can be evenly divided by 1 2 3 4 6 8 9 11 12 16 18 22 24 27 32 33 36 44 48 54 64 66 72 81 88 96 99 108 121 132 144 162 176 192 198 216 242 264 288 297 324 352 363 396 432 484 528 576 594 648 704 726 792 864 891 968 1,056 1,089 1,188 1,296 1,452 1,584 1,728 1,782 1,936 2,112 2,178 2,376 2,592 2,904 3,168 3,267 3,564 3,872 4,356 4,752 5,184 5,808 6,336 6,534 7,128 7,744 8,712 9,504 9,801 11,616 13,068 14,256 17,424 19,008 19,602 23,232 26,136 28,512 34,848 39,204 52,272 57,024 69,696 78,408 104,544 156,816 209,088 313,632 and 627,264, with no remainder.
Since 627,264 cannot be divided by just 1 and 627,264, it is not a prime number.