A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1333860 can be evenly divided by 1 2 3 4 5 6 10 11 12 15 20 22 30 33 43 44 47 55 60 66 86 94 110 129 132 141 165 172 188 215 220 235 258 282 330 430 470 473 516 517 564 645 660 705 860 940 946 1,034 1,290 1,410 1,419 1,551 1,892 2,021 2,068 2,365 2,580 2,585 2,820 2,838 3,102 4,042 4,730 5,170 5,676 6,063 6,204 7,095 7,755 8,084 9,460 10,105 10,340 12,126 14,190 15,510 20,210 22,231 24,252 28,380 30,315 31,020 40,420 44,462 60,630 66,693 88,924 111,155 121,260 133,386 222,310 266,772 333,465 444,620 666,930 and 1,333,860, with no remainder.
Since 1,333,860 cannot be divided by just 1 and 1,333,860, it is not a prime number.