A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4737408 can be evenly divided by 1 2 3 4 6 8 12 13 16 24 26 32 39 48 52 64 73 78 96 104 128 146 156 169 192 208 219 292 312 338 384 416 438 507 584 624 676 832 876 949 1,014 1,168 1,248 1,352 1,664 1,752 1,898 2,028 2,336 2,496 2,704 2,847 3,504 3,796 4,056 4,672 4,992 5,408 5,694 7,008 7,592 8,112 9,344 10,816 11,388 12,337 14,016 15,184 16,224 21,632 22,776 24,674 28,032 30,368 32,448 37,011 45,552 49,348 60,736 64,896 74,022 91,104 98,696 121,472 148,044 182,208 197,392 296,088 364,416 394,784 592,176 789,568 1,184,352 1,579,136 2,368,704 and 4,737,408, with no remainder.
Since 4,737,408 cannot be divided by just 1 and 4,737,408, it is not a prime number.