The number 585,900 can be evenly divided by 1 2 3 4 5 6 7 9 10 12 14 15 18 20 21 25 27 28 30 31 35 36 42 45 50 54 60 62 63 70 75 84 90 93 100 105 108 124 126 135 140 150 155 175 180 186 189 210 217 225 252 270 279 300 310 315 350 372 378 420 434 450 465 525 540 558 620 630 651 675 700 756 775 837 868 900 930 945 1,050 1,085 1,116 1,260 1,302 1,350 1,395 1,550 1,575 1,674 1,860 1,890 1,953 2,100 2,170 2,325 2,604 2,700 2,790 3,100 3,150 3,255 3,348 3,780 3,906 4,185 4,340 4,650 4,725 5,425 5,580 5,859 6,300 6,510 6,975 7,812 8,370 9,300 9,450 9,765 10,850 11,718 13,020 13,950 16,275 16,740 18,900 19,530 20,925 21,700 23,436 27,900 29,295 32,550 39,060 41,850 48,825 58,590 65,100 83,700 97,650 117,180 146,475 195,300 292,950 and 585,900, with no remainder.
Since 585,900 cannot be divided by just 1 and 585,900, it is a composite number.