A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3747450 can be evenly divided by 1 2 3 5 6 7 10 14 15 21 25 30 35 42 43 50 70 75 83 86 105 129 150 166 175 210 215 249 258 301 350 415 430 498 525 581 602 645 830 903 1,050 1,075 1,162 1,245 1,290 1,505 1,743 1,806 2,075 2,150 2,490 2,905 3,010 3,225 3,486 3,569 4,150 4,515 5,810 6,225 6,450 7,138 7,525 8,715 9,030 10,707 12,450 14,525 15,050 17,430 17,845 21,414 22,575 24,983 29,050 35,690 43,575 45,150 49,966 53,535 74,949 87,150 89,225 107,070 124,915 149,898 178,450 249,830 267,675 374,745 535,350 624,575 749,490 1,249,150 1,873,725 and 3,747,450, with no remainder.
Since 3,747,450 cannot be divided by just 1 and 3,747,450, it is not a prime number.