SELECT T2.Name FROM party_host AS T1 JOIN HOST AS T2 ON T1.Host_ID  =  T2.Host_ID JOIN party AS T3 ON T1.Party_ID  =  T3.Party_ID WHERE T3.Number_of_hosts  >  20
Which parties have more than 20 hosts? Give me the host names for these parties.
[Schema (values) (types)]: | party_host |  party : party_id (text) , party_theme (number) , location (text) , first_year (text) , last_year (text) , number_of_hosts (text) | host : host_id (text) , name (number) , nationality (text) , age (text) | party_host : party_id (text) , host_id (number) , is_main_in_charge (text);