The number 279,720 can be evenly divided by 1 2 3 4 5 6 7 8 9 10 12 14 15 18 20 21 24 27 28 30 35 36 37 40 42 45 54 56 60 63 70 72 74 84 90 105 108 111 120 126 135 140 148 168 180 185 189 210 216 222 252 259 270 280 296 315 333 360 370 378 420 444 504 518 540 555 630 666 740 756 777 840 888 945 999 1,036 1,080 1,110 1,260 1,295 1,332 1,480 1,512 1,554 1,665 1,890 1,998 2,072 2,220 2,331 2,520 2,590 2,664 3,108 3,330 3,780 3,885 3,996 4,440 4,662 4,995 5,180 6,216 6,660 6,993 7,560 7,770 7,992 9,324 9,990 10,360 11,655 13,320 13,986 15,540 18,648 19,980 23,310 27,972 31,080 34,965 39,960 46,620 55,944 69,930 93,240 139,860 and 279,720, with no remainder.
Since 279,720 cannot be divided by just 1 and 279,720, it is a composite number.