A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3312660 can be evenly divided by 1 2 3 4 5 6 10 12 13 15 20 26 30 31 39 52 60 62 65 78 93 124 130 137 155 156 186 195 260 274 310 372 390 403 411 465 548 620 685 780 806 822 930 1,209 1,370 1,612 1,644 1,781 1,860 2,015 2,055 2,418 2,740 3,562 4,030 4,110 4,247 4,836 5,343 6,045 7,124 8,060 8,220 8,494 8,905 10,686 12,090 12,741 16,988 17,810 21,235 21,372 24,180 25,482 26,715 35,620 42,470 50,964 53,430 55,211 63,705 84,940 106,860 110,422 127,410 165,633 220,844 254,820 276,055 331,266 552,110 662,532 828,165 1,104,220 1,656,330 and 3,312,660, with no remainder.
Since 3,312,660 cannot be divided by just 1 and 3,312,660, it is not a prime number.