To display the number of pages on the user side, I found the code, maybe it will be useful for someone. Just add this code snippet to function.php.

function img_count(){
        $query_img_args = array(
                'post_type' => 'attachment',
                'post_mime_type' =>array(
                                'jpg|jpeg|jpe' => 'image/jpeg',
                                'gif' => 'image/gif',
                                'png' => 'image/png',
                                ),
                'post_status' => 'inherit',
                'posts_per_page' => -1,
                );
        $query_img = new WP_Query( $query_img_args );
        echo $query_img->post_count;
}

The second part of the code is needed to indicate the location, where to output number of images from media library.