You read the original number into the variable i, which you keep modifying later in the code until it actually reaches the value 0. So later on when you compare the i to c, you actually compare 0 to c and not the original input from the user.
Furthermore, your code only works for exactly 5 digit long non-negative integral numbers and 0.
Below is a solution for any int input:
// Read a number from the user
printf("Please, enter a number: ");
// Reverse the order of digits
int reversedNumber = 0;
for (int tmp = number; tmp > 0; tmp /= 10)
reversedNumber *= 10;
reversedNumber += tmp % 10;
// Print the result
if (number == reversedNumber)
printf("The number reads the same backward.\n");
printf("The number does not read the same backward.\n");