A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2597490 can be evenly divided by 1 2 3 5 6 7 9 10 14 15 18 19 21 30 31 35 38 42 45 49 57 62 63 70 90 93 95 98 105 114 126 133 147 155 171 186 190 210 217 245 266 279 285 294 310 315 342 399 434 441 465 490 558 570 589 630 651 665 735 798 855 882 930 931 1,085 1,178 1,197 1,302 1,330 1,395 1,470 1,519 1,710 1,767 1,862 1,953 1,995 2,170 2,205 2,394 2,790 2,793 2,945 3,038 3,255 3,534 3,906 3,990 4,123 4,410 4,557 4,655 5,301 5,586 5,890 5,985 6,510 7,595 8,246 8,379 8,835 9,114 9,310 9,765 10,602 11,970 12,369 13,671 13,965 15,190 16,758 17,670 19,530 20,615 22,785 24,738 26,505 27,342 27,930 28,861 37,107 41,230 41,895 45,570 53,010 57,722 61,845 68,355 74,214 83,790 86,583 123,690 136,710 144,305 173,166 185,535 259,749 288,610 371,070 432,915 519,498 865,830 1,298,745 and 2,597,490, with no remainder.
Since 2,597,490 cannot be divided by just 1 and 2,597,490, it is not a prime number.