Passage: There are 47 public airports in Spain. The busiest one is the airport of Madrid (Barajas), with 50 million passengers in 2011, being the world's 15th busiest airport, as well as the European Union's fourth busiest. The airport of Barcelona (El Prat) is also important, with 35 million passengers in 2011, being the world's 31st-busiest airport. Other main airports are located in Majorca (23 million passengers), Málaga (13 million passengers), Las Palmas (Gran Canaria) (11 million passengers), Alicante (10 million passengers) and smaller, with the number of passengers between 4 and 10 million, for example Tenerife (two airports), Valencia, Seville, Bilbao, Ibiza, Lanzarote, Fuerteventura. Also, more than 30 airports with the number of passengers below 4 million.

Question: how many public airports are there in spain?
47