A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3770580 can be evenly divided by 1 2 3 4 5 6 10 11 12 15 20 22 29 30 33 44 55 58 60 66 87 110 116 132 145 165 174 197 220 290 319 330 348 394 435 580 591 638 660 788 870 957 985 1,182 1,276 1,595 1,740 1,914 1,970 2,167 2,364 2,955 3,190 3,828 3,940 4,334 4,785 5,713 5,910 6,380 6,501 8,668 9,570 10,835 11,426 11,820 13,002 17,139 19,140 21,670 22,852 26,004 28,565 32,505 34,278 43,340 57,130 62,843 65,010 68,556 85,695 114,260 125,686 130,020 171,390 188,529 251,372 314,215 342,780 377,058 628,430 754,116 942,645 1,256,860 1,885,290 and 3,770,580, with no remainder.
Since 3,770,580 cannot be divided by just 1 and 3,770,580, it is not a prime number.