The Piano Concerto No. 21 in C major, was completed on March 9, 1785 by Wolfgang Amadeus Mozart, four weeks after the completion of the previous D minor concerto.
The concerto has three movements:
1. Allegro maestoso; in common time. The tempo marking is in Mozart's catalog of his own works, but not in the autograph manuscript.
2. Andante in F major. In both the autograph score and in his personal catalog, Mozart notated the meter as Alla breve.
3. Allegro vivace assai