A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3420000 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 19 20 24 25 30 32 36 38 40 45 48 50 57 60 72 75 76 80 90 95 96 100 114 120 125 144 150 152 160 171 180 190 200 225 228 240 250 285 288 300 304 342 360 375 380 400 450 456 475 480 500 570 600 608 625 684 720 750 760 800 855 900 912 950 1,000 1,125 1,140 1,200 1,250 1,368 1,425 1,440 1,500 1,520 1,710 1,800 1,824 1,875 1,900 2,000 2,250 2,280 2,375 2,400 2,500 2,736 2,850 3,000 3,040 3,420 3,600 3,750 3,800 4,000 4,275 4,500 4,560 4,750 5,000 5,472 5,625 5,700 6,000 6,840 7,125 7,200 7,500 7,600 8,550 9,000 9,120 9,500 10,000 11,250 11,400 11,875 12,000 13,680 14,250 15,000 15,200 17,100 18,000 19,000 20,000 21,375 22,500 22,800 23,750 27,360 28,500 30,000 34,200 35,625 36,000 38,000 42,750 45,000 45,600 47,500 57,000 60,000 68,400 71,250 76,000 85,500 90,000 95,000 106,875 114,000 136,800 142,500 171,000 180,000 190,000 213,750 228,000 285,000 342,000 380,000 427,500 570,000 684,000 855,000 1,140,000 1,710,000 and 3,420,000, with no remainder.
Since 3,420,000 cannot be divided by just 1 and 3,420,000, it is not a prime number.