A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1720200 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 20 24 25 30 40 47 50 60 61 75 94 100 120 122 141 150 183 188 200 235 244 282 300 305 366 376 470 488 564 600 610 705 732 915 940 1,128 1,175 1,220 1,410 1,464 1,525 1,830 1,880 2,350 2,440 2,820 2,867 3,050 3,525 3,660 4,575 4,700 5,640 5,734 6,100 7,050 7,320 8,601 9,150 9,400 11,468 12,200 14,100 14,335 17,202 18,300 22,936 28,200 28,670 34,404 36,600 43,005 57,340 68,808 71,675 86,010 114,680 143,350 172,020 215,025 286,700 344,040 430,050 573,400 860,100 and 1,720,200, with no remainder.
Since 1,720,200 cannot be divided by just 1 and 1,720,200, it is not a prime number.