A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2957240 can be evenly divided by 1 2 4 5 8 10 11 13 20 22 26 40 44 47 52 55 65 88 94 104 110 121 130 143 188 220 235 242 260 286 376 440 470 484 517 520 572 605 611 715 940 968 1,034 1,144 1,210 1,222 1,430 1,573 1,880 2,068 2,420 2,444 2,585 2,860 3,055 3,146 4,136 4,840 4,888 5,170 5,687 5,720 6,110 6,292 6,721 7,865 10,340 11,374 12,220 12,584 13,442 15,730 20,680 22,748 24,440 26,884 28,435 31,460 33,605 45,496 53,768 56,870 62,920 67,210 73,931 113,740 134,420 147,862 227,480 268,840 295,724 369,655 591,448 739,310 1,478,620 and 2,957,240, with no remainder.
Since 2,957,240 cannot be divided by just 1 and 2,957,240, it is not a prime number.