Python Program to Check Palindrome Number

You can check a palindrome number in Python by converting the number to a string and comparing it with its reverse using str(num) == str(num)[::-1].

Examples

Input121

Output121 is a palindrome number

Input123

Output123 is not a palindrome number

Input0

Output0 is a palindrome number

How to Think About It

To check if a number is a palindrome, think of it as a word that reads the same forwards and backwards. Convert the number to a string, then compare the string with its reversed version. If both are the same, the number is a palindrome.

Algorithm

1

Get the input number.

2

Convert the number to a string.

3

Reverse the string.

4

Compare the original string with the reversed string.

5

If they are equal, return that the number is a palindrome.

6

Otherwise, return that it is not a palindrome.

Code

python

num = int(input('Enter a number: '))
num_str = str(num)
if num_str == num_str[::-1]:
    print(f'{num} is a palindrome number')
else:
    print(f'{num} is not a palindrome number')

Output

Enter a number: 121
121 is a palindrome number

Dry Run

Let's trace the number 121 through the code

1

Input number

num = 121

2

Convert to string

num_str = '121'

3

Reverse string

num_str[::-1] = '121'

4

Compare strings

'121' == '121' is True

5

Print result

Output: '121 is a palindrome number'

num_str	num_str[::-1]	Comparison Result
121	121	True

Why This Works

Step 1: Convert number to string

We use str(num) to treat the number like text so we can reverse it easily.

Step 2: Reverse the string

Using num_str[::-1] creates a reversed copy of the string.

Step 3: Compare original and reversed

If both strings are the same, the number reads the same forwards and backwards, so it is a palindrome.

Alternative Approaches

Using arithmetic to reverse number

python

num = int(input('Enter a number: '))
original = num
reverse = 0
while num > 0:
    digit = num % 10
    reverse = reverse * 10 + digit
    num //= 10
if original == reverse:
    print(f'{original} is a palindrome number')
else:
    print(f'{original} is not a palindrome number')

This method uses math to reverse the number without converting to string, which is useful if you want to avoid string operations.

Using recursion to check palindrome

python

def is_palindrome(s):
    if len(s) <= 1:
        return True
    if s[0] != s[-1]:
        return False
    return is_palindrome(s[1:-1])
num = input('Enter a number: ')
if is_palindrome(num):
    print(f'{num} is a palindrome number')
else:
    print(f'{num} is not a palindrome number')

This method uses recursion to check palindrome by comparing first and last characters repeatedly.

Complexity: O(n) time, O(n) space

Time Complexity

The time depends on the number of digits n because reversing the string and comparing takes O(n) time.

Space Complexity

Converting the number to a string and creating its reverse uses O(n) extra space.

Which Approach is Fastest?

The arithmetic method uses O(1) space and is efficient, but string method is simpler and more readable for beginners.

Approach	Time	Space	Best For
String reversal	O(n)	O(n)	Simplicity and readability
Arithmetic reversal	O(n)	O(1)	Memory efficiency and no string use
Recursive check	O(n)	O(n)	Learning recursion and string manipulation