The Broncos donned their alternate orange jerseys and kicked off their 2011 season at home against their AFC West rival Oakland Raiders, the Broncos' first Week 1 home opener since 2004. The Broncos took an early lead in the first quarter, with a 28-yard field goal by placekicker Matt Prater. The Raiders reeled off 16 unanswered points in the second quarter, with a 3-yard touchdown pass from quarterback Jason Campbell to fullback Marcel Reece, followed by three field goals of 37, 21 and 63 yards by placekicker Sebastian Janikowski, the latter of which tied the record for the longest field goal in NFL history. The Broncos responded in the third quarter, with kick returner Eric Decker returning a punt 90 yards for a touchdown, followed by a 30-yard field goal by Prater. The Raiders increased their lead in the fourth quarter, with a 1-yard touchdown run by Campbell. The Broncos tried to rally, with quarterback Kyle Orton throwing a 9-yard touchdown pass to running back Lance Ball. However, Oakland would run out the clock.

Based on the above article, answer a question. How many yards was the shortest field goal?
21