Arequipa is in Peruvian area code 054, which is +51 54 in international format.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
The country code and area code of Amazonas, Peru is 51, (0)41.
I think it's 54
The country code and area code of Ayacucho, Peru is 51, (0)66.
The country code and area code of Ucayali, Peru is 51, (0)61.
The country code and area code of Ancash, Peru is 51, (0)43.
The country code and area code of Cajamarca, Peru is 51, (0)76.
The country code and area code of Huancavelica, Peru is 51, (0)67.
The country code and area code of Ica, Peru is 51, (0)56.
The country code and area code of Lambayeque, Peru is 51, (0)74.
The country code and area code of Loreto, Peru is 51, (0)65.
The country code and area code of Moquegua, Peru is 51, (0)53.
The country code and area code of Pasco, Peru is 51, (0)63.