A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1384488 can be evenly divided by 1 2 3 4 6 7 8 9 12 14 18 21 24 28 36 41 42 56 63 67 72 82 84 123 126 134 164 168 201 246 252 268 287 328 369 402 469 492 504 536 574 603 738 804 861 938 984 1,148 1,206 1,407 1,476 1,608 1,722 1,876 2,296 2,412 2,583 2,747 2,814 2,952 3,444 3,752 4,221 4,824 5,166 5,494 5,628 6,888 8,241 8,442 10,332 10,988 11,256 16,482 16,884 19,229 20,664 21,976 24,723 32,964 33,768 38,458 49,446 57,687 65,928 76,916 98,892 115,374 153,832 173,061 197,784 230,748 346,122 461,496 692,244 and 1,384,488, with no remainder.
Since 1,384,488 cannot be divided by just 1 and 1,384,488, it is not a prime number.