A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4226664 can be evenly divided by 1 2 3 4 6 8 12 13 19 23 24 26 31 38 39 46 52 57 62 69 76 78 92 93 104 114 124 138 152 156 184 186 228 247 248 276 299 312 372 403 437 456 494 552 589 598 713 741 744 806 874 897 988 1,178 1,196 1,209 1,311 1,426 1,482 1,612 1,748 1,767 1,794 1,976 2,139 2,356 2,392 2,418 2,622 2,852 2,964 3,224 3,496 3,534 3,588 4,278 4,712 4,836 5,244 5,681 5,704 5,928 7,068 7,176 7,657 8,556 9,269 9,672 10,488 11,362 13,547 14,136 15,314 17,043 17,112 18,538 22,724 22,971 27,094 27,807 30,628 34,086 37,076 40,641 45,448 45,942 54,188 55,614 61,256 68,172 74,152 81,282 91,884 108,376 111,228 136,344 162,564 176,111 183,768 222,456 325,128 352,222 528,333 704,444 1,056,666 1,408,888 2,113,332 and 4,226,664, with no remainder.
Since 4,226,664 cannot be divided by just 1 and 4,226,664, it is not a prime number.