The number 518,400 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 25 27 30 32 36 40 45 48 50 54 60 64 72 75 80 81 90 96 100 108 120 128 135 144 150 160 162 180 192 200 216 225 240 256 270 288 300 320 324 360 384 400 405 432 450 480 540 576 600 640 648 675 720 768 800 810 864 900 960 1,080 1,152 1,200 1,280 1,296 1,350 1,440 1,600 1,620 1,728 1,800 1,920 2,025 2,160 2,304 2,400 2,592 2,700 2,880 3,200 3,240 3,456 3,600 3,840 4,050 4,320 4,800 5,184 5,400 5,760 6,400 6,480 6,912 7,200 8,100 8,640 9,600 10,368 10,800 11,520 12,960 14,400 16,200 17,280 19,200 20,736 21,600 25,920 28,800 32,400 34,560 43,200 51,840 57,600 64,800 86,400 103,680 129,600 172,800 259,200 and 518,400, with no remainder.
Since 518,400 cannot be divided by just 1 and 518,400, it is a composite number.