A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1667592 can be evenly divided by 1 2 3 4 6 8 9 12 18 19 23 24 36 38 46 53 57 69 72 76 92 106 114 138 152 159 171 184 207 212 228 276 318 342 414 424 437 456 477 552 636 684 828 874 954 1,007 1,219 1,272 1,311 1,368 1,656 1,748 1,908 2,014 2,438 2,622 3,021 3,496 3,657 3,816 3,933 4,028 4,876 5,244 6,042 7,314 7,866 8,056 9,063 9,752 10,488 10,971 12,084 14,628 15,732 18,126 21,942 23,161 24,168 29,256 31,464 36,252 43,884 46,322 69,483 72,504 87,768 92,644 138,966 185,288 208,449 277,932 416,898 555,864 833,796 and 1,667,592, with no remainder.
Since 1,667,592 cannot be divided by just 1 and 1,667,592, it is not a prime number.