A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6315192 can be evenly divided by 1 2 3 4 6 8 9 12 13 18 24 26 27 36 39 52 54 72 78 104 108 117 156 169 173 216 234 312 338 346 351 468 507 519 676 692 702 936 1,014 1,038 1,352 1,384 1,404 1,521 1,557 2,028 2,076 2,249 2,808 3,042 3,114 4,056 4,152 4,498 4,563 4,671 6,084 6,228 6,747 8,996 9,126 9,342 12,168 12,456 13,494 17,992 18,252 18,684 20,241 26,988 29,237 36,504 37,368 40,482 53,976 58,474 60,723 80,964 87,711 116,948 121,446 161,928 175,422 233,896 242,892 263,133 350,844 485,784 526,266 701,688 789,399 1,052,532 1,578,798 2,105,064 3,157,596 and 6,315,192, with no remainder.
Since 6,315,192 cannot be divided by just 1 and 6,315,192, it is not a prime number.