A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6533940 can be evenly divided by 1 2 3 4 5 6 7 10 12 14 15 20 21 28 30 35 42 47 60 70 84 94 105 140 141 188 210 235 282 329 331 420 470 564 658 662 705 940 987 993 1,316 1,324 1,410 1,645 1,655 1,974 1,986 2,317 2,820 3,290 3,310 3,948 3,972 4,634 4,935 4,965 6,580 6,620 6,951 9,268 9,870 9,930 11,585 13,902 15,557 19,740 19,860 23,170 27,804 31,114 34,755 46,340 46,671 62,228 69,510 77,785 93,342 108,899 139,020 155,570 186,684 217,798 233,355 311,140 326,697 435,596 466,710 544,495 653,394 933,420 1,088,990 1,306,788 1,633,485 2,177,980 3,266,970 and 6,533,940, with no remainder.
Since 6,533,940 cannot be divided by just 1 and 6,533,940, it is not a prime number.