A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8672664 can be evenly divided by 1 2 3 4 6 7 8 11 12 13 14 19 21 22 24 26 28 33 38 39 42 44 52 56 57 66 76 77 78 84 88 91 104 114 132 133 143 152 154 156 168 182 209 228 231 247 264 266 273 286 308 312 361 364 399 418 429 456 462 494 532 546 572 616 627 722 728 741 798 836 858 924 988 1,001 1,064 1,083 1,092 1,144 1,254 1,444 1,463 1,482 1,596 1,672 1,716 1,729 1,848 1,976 2,002 2,166 2,184 2,508 2,527 2,717 2,888 2,926 2,964 3,003 3,192 3,432 3,458 3,971 4,004 4,332 4,389 4,693 5,016 5,054 5,187 5,434 5,852 5,928 6,006 6,916 7,581 7,942 8,008 8,151 8,664 8,778 9,386 10,108 10,374 10,868 11,704 11,913 12,012 13,832 14,079 15,162 15,884 16,302 17,556 18,772 19,019 20,216 20,748 21,736 23,826 24,024 27,797 28,158 30,324 31,768 32,604 32,851 35,112 37,544 38,038 41,496 47,652 51,623 55,594 56,316 57,057 60,648 65,208 65,702 76,076 83,391 95,304 98,553 103,246 111,188 112,632 114,114 131,404 152,152 154,869 166,782 197,106 206,492 222,376 228,228 262,808 309,738 333,564 361,361 394,212 412,984 456,456 619,476 667,128 722,722 788,424 1,084,083 1,238,952 1,445,444 2,168,166 2,890,888 4,336,332 and 8,672,664, with no remainder.
Since 8,672,664 cannot be divided by just 1 and 8,672,664, it is not a prime number.