Input a number with any number of digits and output it in reverse order of digits.

[zivoni]

If you for some reason do not want to use Larz60+ suggestion, you can do it directly by "removing" either first or last digit of the input number and use it to construct new "reversed" number.

num = 12345

rev_num = 0
while num:
    rev_num = 10 * rev_num + num % 10   # extracts last digit of num and "appends" to "shifted" rev_num
    num //= 10                          # just shortcut for num = num // 10 - removes "used" digit

print("num = {}, reversed num = {}".format(num, rev_num))

Output:
num = 0, reversed num = 54321

As you can see, it destroys the input number in a process of reverting it. If you need to keep your number, you need to use other variable (or you can put that reverting code into a function).

And if your only problem is to check whether number is a palindrome, then simple check based on Larz60+ code is enough:

str(num) == str(num)[::-1]