It is 37.
37
Greatest . . . 37 Smallest . . . 23
19 x 41 = 779
It is: 37
42
The greatest prime factor of 40 is: 5
37 is a prime number between 30 and 40.
Prime numbers betweeen 30 and 40 are 31 and 37.
66
31 is the only prime number between 30 and 40
37