WordPress: get post_parent title

It looks like you've already got the ID of the parent post, so you can just use this:

<?php
    $parent_post_id = 6;
    $parent_post = get_post($parent_post_id);
    $parent_post_title = $parent_post->post_title;
    echo $parent_post_title;
?>

(Insert your parent post id at $parent_post_id)

Ref: http://codex.wordpress.org/Function_Reference/get_post

echo get_the_title( $post->post_parent );

or

echo get_the_title( X );

Where X is any valid post/page ID.

No need to get a complete post object just for one property.