A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1424808 can be evenly divided by 1 2 3 4 6 7 8 9 11 12 14 18 21 22 24 28 33 36 42 44 56 63 66 72 77 84 88 99 126 132 154 168 198 231 252 257 264 308 396 462 504 514 616 693 771 792 924 1,028 1,386 1,542 1,799 1,848 2,056 2,313 2,772 2,827 3,084 3,598 4,626 5,397 5,544 5,654 6,168 7,196 8,481 9,252 10,794 11,308 14,392 16,191 16,962 18,504 19,789 21,588 22,616 25,443 32,382 33,924 39,578 43,176 50,886 59,367 64,764 67,848 79,156 101,772 118,734 129,528 158,312 178,101 203,544 237,468 356,202 474,936 712,404 and 1,424,808, with no remainder.
Since 1,424,808 cannot be divided by just 1 and 1,424,808, it is not a prime number.