A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4057830 can be evenly divided by 1 2 3 5 6 7 9 10 14 15 18 19 21 27 30 35 38 42 45 54 57 63 70 90 95 105 113 114 126 133 135 171 189 190 210 226 266 270 285 315 339 342 378 399 513 565 570 630 665 678 791 798 855 945 1,017 1,026 1,130 1,197 1,330 1,582 1,695 1,710 1,890 1,995 2,034 2,147 2,373 2,394 2,565 3,051 3,390 3,591 3,955 3,990 4,294 4,746 5,085 5,130 5,985 6,102 6,441 7,119 7,182 7,910 10,170 10,735 11,865 11,970 12,882 14,238 15,029 15,255 17,955 19,323 21,357 21,470 23,730 30,058 30,510 32,205 35,595 35,910 38,646 42,714 45,087 57,969 64,410 71,190 75,145 90,174 96,615 106,785 115,938 135,261 150,290 193,230 213,570 225,435 270,522 289,845 405,783 450,870 579,690 676,305 811,566 1,352,610 2,028,915 and 4,057,830, with no remainder.
Since 4,057,830 cannot be divided by just 1 and 4,057,830, it is not a prime number.