A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4126584 can be evenly divided by 1 2 3 4 6 7 8 11 12 14 21 22 24 28 29 33 42 44 49 56 58 66 77 84 87 88 98 116 121 132 147 154 168 174 196 203 231 232 242 264 294 308 319 348 363 392 406 462 484 539 588 609 616 638 696 726 812 847 924 957 968 1,078 1,176 1,218 1,276 1,421 1,452 1,617 1,624 1,694 1,848 1,914 2,156 2,233 2,436 2,541 2,552 2,842 2,904 3,234 3,388 3,509 3,828 4,263 4,312 4,466 4,872 5,082 5,684 5,929 6,468 6,699 6,776 7,018 7,656 8,526 8,932 10,164 10,527 11,368 11,858 12,936 13,398 14,036 15,631 17,052 17,787 17,864 20,328 21,054 23,716 24,563 26,796 28,072 31,262 34,104 35,574 42,108 46,893 47,432 49,126 53,592 62,524 71,148 73,689 84,216 93,786 98,252 125,048 142,296 147,378 171,941 187,572 196,504 294,756 343,882 375,144 515,823 589,512 687,764 1,031,646 1,375,528 2,063,292 and 4,126,584, with no remainder.
Since 4,126,584 cannot be divided by just 1 and 4,126,584, it is not a prime number.