31

The number 31 comes after 30 and comes before 32. 31 is the number of regular polygons with an odd number of sides that are known to be constructible with compass and straightedge. 31 is the maximum number of days in a month. (January, March, May, July, August, October and December.) 31 is Michael Joseph Piazza's number (one of the New York Mets players.) 31 is one of the 30s numbers. The code for international direct-dial phone calls to the Netherlands. 31 is also the number of letters in Macedonian alphabet. Thirty-one is a card game. 31 is even a type of game played on a backgammon board.