A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3477456 can be evenly divided by 1 2 3 4 6 8 9 12 16 18 19 24 31 36 38 41 48 57 62 72 76 82 93 114 123 124 144 152 164 171 186 228 246 248 279 304 328 342 369 372 456 492 496 558 589 656 684 738 744 779 912 984 1,116 1,178 1,271 1,368 1,476 1,488 1,558 1,767 1,968 2,232 2,337 2,356 2,542 2,736 2,952 3,116 3,534 3,813 4,464 4,674 4,712 5,084 5,301 5,904 6,232 7,011 7,068 7,626 9,348 9,424 10,168 10,602 11,439 12,464 14,022 14,136 15,252 18,696 20,336 21,204 22,878 24,149 28,044 28,272 30,504 37,392 42,408 45,756 48,298 56,088 61,008 72,447 84,816 91,512 96,596 112,176 144,894 183,024 193,192 217,341 289,788 386,384 434,682 579,576 869,364 1,159,152 1,738,728 and 3,477,456, with no remainder.
Since 3,477,456 cannot be divided by just 1 and 3,477,456, it is not a prime number.