A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3379740 can be evenly divided by 1 2 3 4 5 6 7 10 12 13 14 15 20 21 26 28 30 35 39 42 52 60 65 70 78 84 91 105 130 140 156 182 195 210 260 273 364 390 420 455 546 619 780 910 1,092 1,238 1,365 1,820 1,857 2,476 2,730 3,095 3,714 4,333 5,460 6,190 7,428 8,047 8,666 9,285 12,380 12,999 16,094 17,332 18,570 21,665 24,141 25,998 32,188 37,140 40,235 43,330 48,282 51,996 56,329 64,995 80,470 86,660 96,564 112,658 120,705 129,990 160,940 168,987 225,316 241,410 259,980 281,645 337,974 482,820 563,290 675,948 844,935 1,126,580 1,689,870 and 3,379,740, with no remainder.
Since 3,379,740 cannot be divided by just 1 and 3,379,740, it is not a prime number.