The number 1,373,328 can be evenly divided by 1 2 3 4 6 8 9 11 12 16 17 18 22 24 27 33 34 36 44 48 51 54 66 68 72 88 99 102 108 132 136 144 153 176 187 198 204 216 264 272 289 297 306 374 396 408 432 459 528 561 578 594 612 748 792 816 867 918 1,122 1,156 1,188 1,224 1,496 1,584 1,683 1,734 1,836 2,244 2,312 2,376 2,448 2,601 2,992 3,179 3,366 3,468 3,672 4,488 4,624 4,752 5,049 5,202 6,358 6,732 6,936 7,344 7,803 8,976 9,537 10,098 10,404 12,716 13,464 13,872 15,606 19,074 20,196 20,808 25,432 26,928 28,611 31,212 38,148 40,392 41,616 50,864 57,222 62,424 76,296 80,784 85,833 114,444 124,848 152,592 171,666 228,888 343,332 457,776 686,664 and 1,373,328, with no remainder.
Since 1,373,328 cannot be divided by just 1 and 1,373,328, it is a composite number.