A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2634660 can be evenly divided by 1 2 3 4 5 6 7 9 10 12 14 15 17 18 20 21 27 28 30 34 35 36 41 42 45 51 54 60 63 68 70 82 84 85 90 102 105 108 119 123 126 135 140 153 164 170 180 189 204 205 210 238 246 252 255 270 287 306 315 340 357 369 378 410 420 459 476 492 510 540 574 595 612 615 630 697 714 738 756 765 820 861 918 945 1,020 1,071 1,107 1,148 1,190 1,230 1,260 1,394 1,428 1,435 1,476 1,530 1,722 1,785 1,836 1,845 1,890 2,091 2,142 2,214 2,295 2,380 2,460 2,583 2,788 2,870 3,060 3,213 3,444 3,485 3,570 3,690 3,780 4,182 4,284 4,305 4,428 4,590 4,879 5,166 5,355 5,535 5,740 6,273 6,426 6,970 7,140 7,380 7,749 8,364 8,610 9,180 9,758 10,332 10,455 10,710 11,070 12,546 12,852 12,915 13,940 14,637 15,498 16,065 17,220 18,819 19,516 20,910 21,420 22,140 24,395 25,092 25,830 29,274 30,996 31,365 32,130 37,638 38,745 41,820 43,911 48,790 51,660 58,548 62,730 64,260 73,185 75,276 77,490 87,822 94,095 97,580 125,460 131,733 146,370 154,980 175,644 188,190 219,555 263,466 292,740 376,380 439,110 526,932 658,665 878,220 1,317,330 and 2,634,660, with no remainder.
Since 2,634,660 cannot be divided by just 1 and 2,634,660, it is not a prime number.