A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 739908 can be evenly divided by 1 2 3 4 6 9 12 13 17 18 26 27 31 34 36 39 51 52 54 62 68 78 93 102 108 117 124 153 156 186 204 221 234 279 306 351 372 403 442 459 468 527 558 612 663 702 806 837 884 918 1,054 1,116 1,209 1,326 1,404 1,581 1,612 1,674 1,836 1,989 2,108 2,418 2,652 3,162 3,348 3,627 3,978 4,743 4,836 5,967 6,324 6,851 7,254 7,956 9,486 10,881 11,934 13,702 14,229 14,508 18,972 20,553 21,762 23,868 27,404 28,458 41,106 43,524 56,916 61,659 82,212 123,318 184,977 246,636 369,954 and 739,908, with no remainder.
Since 739,908 cannot be divided by just 1 and 739,908, it is not a prime number.