A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2333856 can be evenly divided by 1 2 3 4 6 7 8 12 14 16 21 23 24 28 32 42 46 48 56 69 84 92 96 112 138 151 161 168 184 224 276 302 322 336 368 453 483 552 604 644 672 736 906 966 1,057 1,104 1,208 1,288 1,812 1,932 2,114 2,208 2,416 2,576 3,171 3,473 3,624 3,864 4,228 4,832 5,152 6,342 6,946 7,248 7,728 8,456 10,419 12,684 13,892 14,496 15,456 16,912 20,838 24,311 25,368 27,784 33,824 41,676 48,622 50,736 55,568 72,933 83,352 97,244 101,472 111,136 145,866 166,704 194,488 291,732 333,408 388,976 583,464 777,952 1,166,928 and 2,333,856, with no remainder.
Since 2,333,856 cannot be divided by just 1 and 2,333,856, it is not a prime number.