The number 2,921,688 can be evenly divided by 1 2 3 4 6 7 8 9 11 12 14 17 18 21 22 24 28 31 33 34 36 42 44 51 56 62 63 66 68 72 77 84 88 93 99 102 119 124 126 132 136 153 154 168 186 187 198 204 217 231 238 248 252 264 279 306 308 341 357 372 374 396 408 434 462 476 504 527 558 561 612 616 651 682 693 714 744 748 792 868 924 952 1,023 1,054 1,071 1,116 1,122 1,224 1,302 1,309 1,364 1,386 1,428 1,496 1,581 1,683 1,736 1,848 1,953 2,046 2,108 2,142 2,232 2,244 2,387 2,604 2,618 2,728 2,772 2,856 3,069 3,162 3,366 3,689 3,906 3,927 4,092 4,216 4,284 4,488 4,743 4,774 5,208 5,236 5,544 5,797 6,138 6,324 6,732 7,161 7,378 7,812 7,854 8,184 8,568 9,486 9,548 10,472 11,067 11,594 11,781 12,276 12,648 13,464 14,322 14,756 15,624 15,708 17,391 18,972 19,096 21,483 22,134 23,188 23,562 24,552 28,644 29,512 31,416 33,201 34,782 37,944 40,579 42,966 44,268 46,376 47,124 52,173 57,288 66,402 69,564 81,158 85,932 88,536 94,248 104,346 121,737 132,804 139,128 162,316 171,864 208,692 243,474 265,608 324,632 365,211 417,384 486,948 730,422 973,896 1,460,844 and 2,921,688, with no remainder.
Since 2,921,688 cannot be divided by just 1 and 2,921,688, it is a composite number.