Palindromic numbers (also called palindromes), are numbers such as 7245427 which is the same number when the digits are reversed. Prime palindromes exist, but these must have an odd number of digits. In ENS (base ten), 101 is the first three digit prime palindrome. However in ANS, 101 = A1, so the first prime palindrome in ANS is 131. Some numbers in ENS are also palindromes in ANS. For example, 21 (base 10), is 10101 in binary in ENS and 1221 in binary in ANS, and both are palindromes. On the other hand, 1001001 is a binary palindrome in ENS, but converts to 112121 in ANS, which is not a palindrome.
There is an interesting procedure commonly called the 196-Algorithm, that operates as follows. Select any number with two or more digits. Reverse the number and add it to the original number, and repeat the procedure on the sum until a palindrome results. In ENS, most numbers create palindromes, however, a palindrome for the number 196, has never been found - hence the name of the procedure. An interesting thing happens when ANS is applied to 196 :
196 + 691 = 887
887 + 788 = 1675
1675 + 5761 = 7436
7436 + 6347 = 13783
13783 + 38731 = 52514
52514 + 41525 = 94039
The number 94039 = 93A39 (in ANS) which is a palindrome!
The obvious question is : are there numbers in ANS that don't create palindromes? I have found that such numbers do appear to exist, and the smallest one in base ten, is the number 70 = 6A in ANS. I have examined 6A using this procedure for up to 1000 digits, and have not yet found a palindrome.
There is more information on this procedure on Kevin Brown's Math Pages under Digit Reversal Sums Leading to Palindromes
Also on Eric Weisstein's math pages can be found The 196-Algorithm
If you are interested in palindromes, Patrick DeGeest's web pages are full of fascinating ideas.
Enjoy.