A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2359056 can be evenly divided by 1 2 3 4 6 7 8 12 14 16 17 21 24 28 34 42 48 49 51 56 59 68 84 98 102 112 118 119 136 147 168 177 196 204 236 238 272 294 336 354 357 392 408 413 472 476 588 708 714 784 816 826 833 944 952 1,003 1,176 1,239 1,416 1,428 1,652 1,666 1,904 2,006 2,352 2,478 2,499 2,832 2,856 2,891 3,009 3,304 3,332 4,012 4,956 4,998 5,712 5,782 6,018 6,608 6,664 7,021 8,024 8,673 9,912 9,996 11,564 12,036 13,328 14,042 16,048 17,346 19,824 19,992 21,063 23,128 24,072 28,084 34,692 39,984 42,126 46,256 48,144 49,147 56,168 69,384 84,252 98,294 112,336 138,768 147,441 168,504 196,588 294,882 337,008 393,176 589,764 786,352 1,179,528 and 2,359,056, with no remainder.
Since 2,359,056 cannot be divided by just 1 and 2,359,056, it is not a prime number.