A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4326588 can be evenly divided by 1 2 3 4 6 7 9 12 14 18 21 27 28 36 42 54 59 63 84 97 108 118 126 177 189 194 236 252 291 354 378 388 413 531 582 679 708 756 826 873 1,062 1,164 1,239 1,358 1,593 1,652 1,746 2,037 2,124 2,478 2,619 2,716 3,186 3,492 3,717 4,074 4,956 5,238 5,723 6,111 6,372 7,434 8,148 10,476 11,151 11,446 12,222 14,868 17,169 18,333 22,302 22,892 24,444 34,338 36,666 40,061 44,604 51,507 68,676 73,332 80,122 103,014 120,183 154,521 160,244 206,028 240,366 309,042 360,549 480,732 618,084 721,098 1,081,647 1,442,196 2,163,294 and 4,326,588, with no remainder.
Since 4,326,588 cannot be divided by just 1 and 4,326,588, it is not a prime number.