A palindromic number is a number that remains the same when its digits are reversed. For example, the number 121 reads the same forwards and backwards, making it a palindrome. Palindromic numbers can be found in various numerical systems, including decimal and binary. These numbers can have any number of digits, such as 7, 44, or 12321. Palindromic numbers are often used in recreational mathematics and can be interesting to explore due to their unique symmetrical properties.