A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5658120 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 13 15 18 20 24 26 27 30 31 36 39 40 45 52 54 60 62 65 72 78 90 93 104 108 117 120 124 130 135 155 156 169 180 186 195 216 234 248 260 270 279 310 312 338 351 360 372 390 403 465 468 507 520 540 558 585 620 676 702 744 780 806 837 845 930 936 1,014 1,080 1,116 1,170 1,209 1,240 1,352 1,395 1,404 1,521 1,560 1,612 1,674 1,690 1,755 1,860 2,015 2,028 2,232 2,340 2,418 2,535 2,790 2,808 3,042 3,224 3,348 3,380 3,510 3,627 3,720 4,030 4,056 4,185 4,563 4,680 4,836 5,070 5,239 5,580 6,045 6,084 6,696 6,760 7,020 7,254 7,605 8,060 8,370 9,126 9,672 10,140 10,478 10,881 11,160 12,090 12,168 14,040 14,508 15,210 15,717 16,120 16,740 18,135 18,252 20,280 20,956 21,762 22,815 24,180 26,195 29,016 30,420 31,434 33,480 36,270 36,504 41,912 43,524 45,630 47,151 48,360 52,390 54,405 60,840 62,868 72,540 78,585 87,048 91,260 94,302 104,780 108,810 125,736 141,453 145,080 157,170 182,520 188,604 209,560 217,620 235,755 282,906 314,340 377,208 435,240 471,510 565,812 628,680 707,265 943,020 1,131,624 1,414,530 1,886,040 2,829,060 and 5,658,120, with no remainder.
Since 5,658,120 cannot be divided by just 1 and 5,658,120, it is not a prime number.