A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2542320 can be evenly divided by 1 2 3 4 5 6 8 9 10 11 12 15 16 18 20 22 24 27 30 33 36 40 44 45 48 54 55 60 66 72 80 88 90 99 107 108 110 120 132 135 144 165 176 180 198 214 216 220 240 264 270 297 321 330 360 396 428 432 440 495 528 535 540 594 642 660 720 792 856 880 963 990 1,070 1,080 1,177 1,188 1,284 1,320 1,485 1,584 1,605 1,712 1,926 1,980 2,140 2,160 2,354 2,376 2,568 2,640 2,889 2,970 3,210 3,531 3,852 3,960 4,280 4,708 4,752 4,815 5,136 5,778 5,885 5,940 6,420 7,062 7,704 7,920 8,560 9,416 9,630 10,593 11,556 11,770 11,880 12,840 14,124 14,445 15,408 17,655 18,832 19,260 21,186 23,112 23,540 23,760 25,680 28,248 28,890 31,779 35,310 38,520 42,372 46,224 47,080 52,965 56,496 57,780 63,558 70,620 77,040 84,744 94,160 105,930 115,560 127,116 141,240 158,895 169,488 211,860 231,120 254,232 282,480 317,790 423,720 508,464 635,580 847,440 1,271,160 and 2,542,320, with no remainder.
Since 2,542,320 cannot be divided by just 1 and 2,542,320, it is not a prime number.