Unscrambling the letters in RUNNING makes 22 valid words. Here is the full breakdown — longest words, top Scrabble scores, and every word grouped by length (highest-scoring first).
Word lengths: 7-letter (1), 5-letter (3), 4-letter (5), 3-letter (10), 2-letter (3). There are 1 seven-letter words here — each is a potential Scrabble bingo worth a 50-point bonus.