A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4551240 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 17 20 23 24 30 34 40 46 51 60 68 69 85 92 97 102 115 120 136 138 170 184 194 204 230 255 276 291 340 345 388 391 408 460 485 510 552 582 680 690 776 782 920 970 1,020 1,164 1,173 1,380 1,455 1,564 1,649 1,940 1,955 2,040 2,231 2,328 2,346 2,760 2,910 3,128 3,298 3,880 3,910 4,462 4,692 4,947 5,820 5,865 6,596 6,693 7,820 8,245 8,924 9,384 9,894 11,155 11,640 11,730 13,192 13,386 15,640 16,490 17,848 19,788 22,310 23,460 24,735 26,772 32,980 33,465 37,927 39,576 44,620 46,920 49,470 53,544 65,960 66,930 75,854 89,240 98,940 113,781 133,860 151,708 189,635 197,880 227,562 267,720 303,416 379,270 455,124 568,905 758,540 910,248 1,137,810 1,517,080 2,275,620 and 4,551,240, with no remainder.
Since 4,551,240 cannot be divided by just 1 and 4,551,240, it is not a prime number.