Formatting values fetched from dirty datastore

Is it possible to format data which is fetched from dirty? For example, 83647 to be formatted as 83,647. I have the following code for unformatted data:

db.on('load', function() {
  db.set('john', {completed: '83647'});
  console.log('John's completed tasks are: %s', db.get('john').completed);
});