A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2223456 can be evenly divided by 1 2 3 4 6 8 12 16 19 23 24 32 38 46 48 53 57 69 76 92 96 106 114 138 152 159 184 212 228 276 304 318 368 424 437 456 552 608 636 736 848 874 912 1,007 1,104 1,219 1,272 1,311 1,696 1,748 1,824 2,014 2,208 2,438 2,544 2,622 3,021 3,496 3,657 4,028 4,876 5,088 5,244 6,042 6,992 7,314 8,056 9,752 10,488 12,084 13,984 14,628 16,112 19,504 20,976 23,161 24,168 29,256 32,224 39,008 41,952 46,322 48,336 58,512 69,483 92,644 96,672 117,024 138,966 185,288 277,932 370,576 555,864 741,152 1,111,728 and 2,223,456, with no remainder.
Since 2,223,456 cannot be divided by just 1 and 2,223,456, it is not a prime number.