A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4636665 can be evenly divided by 1 3 5 9 11 15 17 19 29 33 45 51 55 57 85 87 95 99 145 153 165 171 187 209 255 261 285 319 323 435 493 495 551 561 627 765 855 935 957 969 1,045 1,305 1,479 1,595 1,615 1,653 1,683 1,881 2,465 2,755 2,805 2,871 2,907 3,135 3,553 4,437 4,785 4,845 4,959 5,423 6,061 7,395 8,265 8,415 9,367 9,405 10,659 14,355 14,535 16,269 17,765 18,183 22,185 24,795 27,115 28,101 30,305 31,977 46,835 48,807 53,295 54,549 81,345 84,303 90,915 103,037 140,505 159,885 244,035 272,745 309,111 421,515 515,185 927,333 1,545,555 and 4,636,665, with no remainder.
Since 4,636,665 cannot be divided by just 1 and 4,636,665, it is not a prime number.