The number 1,578,960 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 17 18 20 24 27 30 34 36 40 43 45 48 51 54 60 68 72 80 85 86 90 102 108 120 129 135 136 144 153 170 172 180 204 215 216 240 255 258 270 272 306 340 344 360 387 408 430 432 459 510 516 540 612 645 680 688 720 731 765 774 816 860 918 1,020 1,032 1,080 1,161 1,224 1,290 1,360 1,462 1,530 1,548 1,720 1,836 1,935 2,040 2,064 2,160 2,193 2,295 2,322 2,448 2,580 2,924 3,060 3,096 3,440 3,655 3,672 3,870 4,080 4,386 4,590 4,644 5,160 5,805 5,848 6,120 6,192 6,579 7,310 7,344 7,740 8,772 9,180 9,288 10,320 10,965 11,610 11,696 12,240 13,158 14,620 15,480 17,544 18,360 18,576 19,737 21,930 23,220 26,316 29,240 30,960 32,895 35,088 36,720 39,474 43,860 46,440 52,632 58,480 65,790 78,948 87,720 92,880 98,685 105,264 131,580 157,896 175,440 197,370 263,160 315,792 394,740 526,320 789,480 and 1,578,960, with no remainder.
Since 1,578,960 cannot be divided by just 1 and 1,578,960, it is a composite number.