A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1703400 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 17 20 24 25 30 34 40 50 51 60 68 75 85 100 102 120 136 150 167 170 200 204 255 300 334 340 408 425 501 510 600 668 680 835 850 1,002 1,020 1,275 1,336 1,670 1,700 2,004 2,040 2,505 2,550 2,839 3,340 3,400 4,008 4,175 5,010 5,100 5,678 6,680 8,350 8,517 10,020 10,200 11,356 12,525 14,195 16,700 17,034 20,040 22,712 25,050 28,390 33,400 34,068 42,585 50,100 56,780 68,136 70,975 85,170 100,200 113,560 141,950 170,340 212,925 283,900 340,680 425,850 567,800 851,700 and 1,703,400, with no remainder.
Since 1,703,400 cannot be divided by just 1 and 1,703,400, it is not a prime number.