A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4315872 can be evenly divided by 1 2 3 4 6 8 11 12 16 22 24 32 33 44 48 61 66 67 88 96 122 132 134 176 183 201 244 264 268 352 366 402 488 528 536 671 732 737 804 976 1,056 1,072 1,342 1,464 1,474 1,608 1,952 2,013 2,144 2,211 2,684 2,928 2,948 3,216 4,026 4,087 4,422 5,368 5,856 5,896 6,432 8,052 8,174 8,844 10,736 11,792 12,261 16,104 16,348 17,688 21,472 23,584 24,522 32,208 32,696 35,376 44,957 49,044 64,416 65,392 70,752 89,914 98,088 130,784 134,871 179,828 196,176 269,742 359,656 392,352 539,484 719,312 1,078,968 1,438,624 2,157,936 and 4,315,872, with no remainder.
Since 4,315,872 cannot be divided by just 1 and 4,315,872, it is not a prime number.