A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 520800 can be evenly divided by 1 2 3 4 5 6 7 8 10 12 14 15 16 20 21 24 25 28 30 31 32 35 40 42 48 50 56 60 62 70 75 80 84 93 96 100 105 112 120 124 140 150 155 160 168 175 186 200 210 217 224 240 248 280 300 310 336 350 372 400 420 434 465 480 496 525 560 600 620 651 672 700 744 775 800 840 868 930 992 1,050 1,085 1,120 1,200 1,240 1,302 1,400 1,488 1,550 1,680 1,736 1,860 2,100 2,170 2,325 2,400 2,480 2,604 2,800 2,976 3,100 3,255 3,360 3,472 3,720 4,200 4,340 4,650 4,960 5,208 5,425 5,600 6,200 6,510 6,944 7,440 8,400 8,680 9,300 10,416 10,850 12,400 13,020 14,880 16,275 16,800 17,360 18,600 20,832 21,700 24,800 26,040 32,550 34,720 37,200 43,400 52,080 65,100 74,400 86,800 104,160 130,200 173,600 260,400 and 520,800, with no remainder.
Since 520,800 cannot be divided by just 1 and 520,800, it is not a prime number.