Complex sentence: A chess prodigy, he achieved his grandmaster title in 2013 at the age of 15 years and 21 days, becoming the second youngest grandmaster in the world after Wei Yi at the time.
Split into simpler sentences: A chess prodigy, he achieved his grandmaster title in 2013 at the age of 15 years and 21 days. This made him the second youngest grandmaster in the world at the time.