Actually I don't know how many altcoin are in the cryptocurrency world. but i know just listed on coinmarketcap have more then 1320 types altcoin.
Just you see here:
https://coinmarketcap.com/all/views/all/I think coinmarketcap by far doesn't list all the coins nowadays. There are more than 40 new ICOs a day now. No Chance to have them all on the exchanges