A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6003660 can be evenly divided by 1 2 3 4 5 6 10 12 13 15 20 26 30 39 43 52 60 65 78 86 129 130 156 172 179 195 215 258 260 358 390 430 516 537 559 645 716 780 860 895 1,074 1,118 1,290 1,677 1,790 2,148 2,236 2,327 2,580 2,685 2,795 3,354 3,580 4,654 5,370 5,590 6,708 6,981 7,697 8,385 9,308 10,740 11,180 11,635 13,962 15,394 16,770 23,091 23,270 27,924 30,788 33,540 34,905 38,485 46,182 46,540 69,810 76,970 92,364 100,061 115,455 139,620 153,940 200,122 230,910 300,183 400,244 461,820 500,305 600,366 1,000,610 1,200,732 1,500,915 2,001,220 3,001,830 and 6,003,660, with no remainder.
Since 6,003,660 cannot be divided by just 1 and 6,003,660, it is not a prime number.