The no. is 35.
Find a four digit number whose digits will be reversed when multiplied by nine?
If the number with the digits reversed can have a leading 0 so that it is a 1-digit number, then 16. Otherwise 13.
93 (and 39).
An eight digit number with one zero cannot remain the same when its digits are reversed. It must have an even number of 0s.
45 and 54