What is a palindrome number?

A palindrome number is a number that reads the same forwards and backwards.

How to check if a number is palindrome?

Convert the number to a string and check if it reads the same from left to right and right to left.

21 is not a palindrome number.

A palindrome number reads the same forwards and backwards. For example, 121 and 1331 are palindrome numbers, while 123 is not.

To check if 21 is palindrome, convert it to a string and compare it with its reverse.

Because the reverse of 21 is 12, which is different from the original number.

Can single-digit numbers be palindrome?

Yes, all single-digit numbers (0-9) are palindrome numbers.
Are palindrome numbers only positive?

Palindrome numbers are typically considered positive integers, but the concept can be extended to other contexts.
Why are palindrome numbers important?

They have applications in computer science, coding theory, and recreational math problems.