iTunes Radio already has 20M users a month after September launch

Apple said its new streaming music service iTunes Radio has about 20 million listeners, the company revealed during today’s big media event in San Francisco.

The listener numbers have nearly doubled since the last time Apple shed some light on the streaming service’s usage just a week after launching back in September.

iTunes Radio functions quite a bit like Pandora, the leading streaming radio service in the U.S. You create smart radio stations based on a song or artist that’s already within your music library. For perspective, however, Pandora currently has 72.7 million listeners — and is actually able to generate revenue from the service from advertising.

Apple didn’t really offer any other details about iTunes Radio’s listener base. That means we don’t know how many hours people are listening to music on the service or how often they are returning to use it.