add "items_per_page" number in title tag and meta tag
I got a solution. Just add the following code in template.php file.

function yourtheme_preprocess_html(&amp;$vars){
    // add pager number to title.
    parse_str($_SERVER['QUERY_STRING']);
    if(isset($items_per_page)){
        $vars['head_title'] .= $items_per_page;
    }
}