A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6040020 can be evenly divided by 1 2 3 4 5 6 7 10 12 14 15 20 21 28 30 35 42 60 70 73 84 105 140 146 197 210 219 292 365 394 420 438 511 591 730 788 876 985 1,022 1,095 1,182 1,379 1,460 1,533 1,970 2,044 2,190 2,364 2,555 2,758 2,955 3,066 3,940 4,137 4,380 5,110 5,516 5,910 6,132 6,895 7,665 8,274 10,220 11,820 13,790 14,381 15,330 16,548 20,685 27,580 28,762 30,660 41,370 43,143 57,524 71,905 82,740 86,286 100,667 143,810 172,572 201,334 215,715 287,620 302,001 402,668 431,430 503,335 604,002 862,860 1,006,670 1,208,004 1,510,005 2,013,340 3,020,010 and 6,040,020, with no remainder.
Since 6,040,020 cannot be divided by just 1 and 6,040,020, it is not a prime number.