A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1466496 can be evenly divided by 1 2 3 4 6 8 9 12 16 18 19 24 32 36 38 48 57 64 67 72 76 96 114 128 134 144 152 171 192 201 228 268 288 304 342 384 402 456 536 576 603 608 684 804 912 1,072 1,152 1,206 1,216 1,273 1,368 1,608 1,824 2,144 2,412 2,432 2,546 2,736 3,216 3,648 3,819 4,288 4,824 5,092 5,472 6,432 7,296 7,638 8,576 9,648 10,184 10,944 11,457 12,864 15,276 19,296 20,368 21,888 22,914 25,728 30,552 38,592 40,736 45,828 61,104 77,184 81,472 91,656 122,208 162,944 183,312 244,416 366,624 488,832 733,248 and 1,466,496, with no remainder.
Since 1,466,496 cannot be divided by just 1 and 1,466,496, it is not a prime number.