What do you have in SETTINGS => GENERAL (under WordPress Address & Site Address)?
If you have the IP there, change both fields to the domain name.
Any other advantage to set up the address in wordpress?
SEO, for one. Having the same content available from different addresses (often called “Duplicate Content” problem) may cause all sorts of search engine indexing, ranking, and reporting issues.
If SEO is a non-issue for you, here’s another potential problem: all images and other files uploaded from the WordPress interface will use the configured address in the file’s URL. So if your site has the IP address (instead of the domain name), then all the images and other files on your site will use the IP address for their URLs.
These absolute URLs are stored in the database.
This will work fine… until you ever need to move your site to a new server (meaning a new IP address!). Then all the images on your site will be completely broken.