A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5245758 can be evenly divided by 1 2 3 6 7 9 14 17 18 21 31 34 42 51 62 63 79 93 102 119 126 153 158 186 217 237 238 279 306 357 434 474 527 553 558 651 711 714 1,054 1,071 1,106 1,302 1,343 1,422 1,581 1,659 1,953 2,142 2,449 2,686 3,162 3,318 3,689 3,906 4,029 4,743 4,898 4,977 7,347 7,378 8,058 9,401 9,486 9,954 11,067 12,087 14,694 17,143 18,802 22,041 22,134 24,174 28,203 33,201 34,286 41,633 44,082 51,429 56,406 66,402 83,266 84,609 102,858 124,899 154,287 169,218 249,798 291,431 308,574 374,697 582,862 749,394 874,293 1,748,586 2,622,879 and 5,245,758, with no remainder.
Since 5,245,758 cannot be divided by just 1 and 5,245,758, it is not a prime number.