The number 681,912 can be evenly divided by 1 2 3 4 6 7 8 9 11 12 14 18 21 22 24 27 28 33 36 41 42 44 54 56 63 66 72 77 82 84 88 99 108 123 126 132 154 164 168 189 198 216 231 246 252 264 287 297 308 328 369 378 396 451 462 492 504 574 594 616 693 738 756 792 861 902 924 984 1,107 1,148 1,188 1,353 1,386 1,476 1,512 1,722 1,804 1,848 2,079 2,214 2,296 2,376 2,583 2,706 2,772 2,952 3,157 3,444 3,608 4,059 4,158 4,428 5,166 5,412 5,544 6,314 6,888 7,749 8,118 8,316 8,856 9,471 10,332 10,824 12,177 12,628 15,498 16,236 16,632 18,942 20,664 24,354 25,256 28,413 30,996 32,472 37,884 48,708 56,826 61,992 75,768 85,239 97,416 113,652 170,478 227,304 340,956 and 681,912, with no remainder.
Since 681,912 cannot be divided by just 1 and 681,912, it is a composite number.