It is 19 which is a prime number
n - 4 = 19
A number cannot be "less than but more than 40".
Answer -19
19
The greatest prime number less than 20 is 19. For there to be a difference, we'll have to have another value.
There are a few numbers that are less than 19 and have more than 4 factors. The number 10 is less than 19 and has more than four factors.
19
29
19
-19?
The number is: 233-169+19 = 83
It is 19 which is a prime number
n - 4 = 19
27
Because the sum of its proper divisors is less than 19.
A number cannot be "less than but more than 40".