A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3072432 can be evenly divided by 1 2 3 4 6 8 11 12 16 22 23 24 33 44 46 48 66 69 88 92 121 132 138 176 184 242 253 264 276 363 368 484 506 528 529 552 726 759 968 1,012 1,058 1,104 1,452 1,518 1,587 1,936 2,024 2,116 2,783 2,904 3,036 3,174 4,048 4,232 5,566 5,808 5,819 6,072 6,348 8,349 8,464 11,132 11,638 12,144 12,696 16,698 17,457 22,264 23,276 25,392 33,396 34,914 44,528 46,552 64,009 66,792 69,828 93,104 128,018 133,584 139,656 192,027 256,036 279,312 384,054 512,072 768,108 1,024,144 1,536,216 and 3,072,432, with no remainder.
Since 3,072,432 cannot be divided by just 1 and 3,072,432, it is not a prime number.