A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3735810 can be evenly divided by 1 2 3 5 6 9 10 13 15 18 26 30 31 39 45 62 65 78 90 93 103 117 130 155 186 195 206 234 279 309 310 390 403 465 515 558 585 618 806 927 930 1,030 1,170 1,209 1,339 1,395 1,545 1,854 2,015 2,418 2,678 2,790 3,090 3,193 3,627 4,017 4,030 4,635 6,045 6,386 6,695 7,254 8,034 9,270 9,579 12,051 12,090 13,390 15,965 18,135 19,158 20,085 24,102 28,737 31,930 36,270 40,170 41,509 47,895 57,474 60,255 83,018 95,790 120,510 124,527 143,685 207,545 249,054 287,370 373,581 415,090 622,635 747,162 1,245,270 1,867,905 and 3,735,810, with no remainder.
Since 3,735,810 cannot be divided by just 1 and 3,735,810, it is not a prime number.