A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1607112 can be evenly divided by 1 2 3 4 6 8 9 12 13 17 18 24 26 34 36 39 51 52 68 72 78 101 102 104 117 136 153 156 202 204 221 234 303 306 312 404 408 442 468 606 612 663 808 884 909 936 1,212 1,224 1,313 1,326 1,717 1,768 1,818 1,989 2,424 2,626 2,652 3,434 3,636 3,939 3,978 5,151 5,252 5,304 6,868 7,272 7,878 7,956 10,302 10,504 11,817 13,736 15,453 15,756 15,912 20,604 22,321 23,634 30,906 31,512 41,208 44,642 47,268 61,812 66,963 89,284 94,536 123,624 133,926 178,568 200,889 267,852 401,778 535,704 803,556 and 1,607,112, with no remainder.
Since 1,607,112 cannot be divided by just 1 and 1,607,112, it is not a prime number.