A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1717170 can be evenly divided by 1 2 3 5 6 7 10 13 14 15 17 21 26 30 34 35 37 39 42 51 65 70 74 78 85 91 102 105 111 119 130 170 182 185 195 210 221 222 238 255 259 273 357 370 390 442 455 481 510 518 546 555 595 629 663 714 777 910 962 1,105 1,110 1,190 1,258 1,295 1,326 1,365 1,443 1,547 1,554 1,785 1,887 2,210 2,405 2,590 2,730 2,886 3,094 3,145 3,315 3,367 3,570 3,774 3,885 4,403 4,641 4,810 6,290 6,630 6,734 7,215 7,735 7,770 8,177 8,806 9,282 9,435 10,101 13,209 14,430 15,470 16,354 16,835 18,870 20,202 22,015 23,205 24,531 26,418 33,670 40,885 44,030 46,410 49,062 50,505 57,239 66,045 81,770 101,010 114,478 122,655 132,090 171,717 245,310 286,195 343,434 572,390 858,585 and 1,717,170, with no remainder.
Since 1,717,170 cannot be divided by just 1 and 1,717,170, it is not a prime number.