A palindromic number is a symmetrical number like 16461,
that remains the same when its digits are reversed. The term
palindromic is derived from palindrome, which refers to a
word like rotor that remains unchanged under reversal of its
letters.

171 23632 55
8998 7346437,... are examples of palindromic numbers. Their
digits read the same backwards as forwards. Palindromic numbers
receive most attention in the realm of recreational mathematics.
The palindromic primes are 2, 3, 5, 7, 11, 101, 131, 151, ...

The palindromic square numbers are 0, 1, 4, 9, 121, 484, 676, 10201,
12321. Palindromic numbers can be considered in other numeral systems
than decimal. For example, the binary palindromic numbers are
0, 1, 11, 101,
111, 1001, 1111, 10001, 10101, 11011, 11111, 100001, ...