A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2671890 can be evenly divided by 1 2 3 5 6 10 13 15 17 26 30 31 34 39 51 62 65 78 85 93 102 130 155 169 170 186 195 221 255 310 338 390 403 442 465 507 510 527 663 806 845 930 1,014 1,054 1,105 1,209 1,326 1,581 1,690 2,015 2,210 2,418 2,535 2,635 2,873 3,162 3,315 4,030 5,070 5,239 5,270 5,746 6,045 6,630 6,851 7,905 8,619 10,478 12,090 13,702 14,365 15,717 15,810 17,238 20,553 26,195 28,730 31,434 34,255 41,106 43,095 52,390 68,510 78,585 86,190 89,063 102,765 157,170 178,126 205,530 267,189 445,315 534,378 890,630 1,335,945 and 2,671,890, with no remainder.
Since 2,671,890 cannot be divided by just 1 and 2,671,890, it is not a prime number.