Daniel J. Lewis of The Audacity to Podcast has been doing some deep diving on numbers in the podcasting space looking specifically at shows in Apple Podcasts through their API and have come up with some stats that are absolute gold.  See more stats here.

Total Feeds
Almost 609K total podcasts in Apple Podcasts.

83K SoundCloud feeds
72k Anchor feeds
50K FeedBurner feeds
40K Libsyn feeds
28.3K Podbean feeds
27K Blubrry / PowerPress feeds
15.1K Spreaker feeds
8.2K Buzzsprout feeds
3.2K Simplecast feeds
2K Libsyn Pro feeds
1.1K podcasts.com feeds
1K Podtrac feeds
600 Fireside feeds

Some Interesting Metrics in relationships to the number of Episodes in the feeds

58K of the Anchor feeds have 10 or fewer episodes.
50K of the SoundCloud feeds have 10 or fewer episodes.
11K of Libsyn feeds have 10 or fewer.
A little more than half of all podcasts in AP have 10 or fewer episodes!
78.5K feeds in AP have only 1 episode!

When Daniel looked at the 3 or fewer episode metric per feed the breakdown even gets more wide-eyed.

42.4K Anchor feeds have 3 or fewer episodes
27.2K for SoundCloud
8.4K for FeedBurner
3.6K for Libsyn
3.3K for Blubrry / PowerPress
158.7K podcasts in all of AP have 3 or fewer episodes.

Overall Stats
263.3K (43.2%) of podcasts haven’t released an episode at all this year.

When Looking at Apple Podcast to see how many shows have the correct link back to there .com here is the breakdown.

-Of the 40.8K Libsyn-domain feeds in Apple Podcasts, more than half have their website properly set to something other than a Libsyn domain. Leaving 18.3K Libsyn-domain feeds pointing to Libsyn-domain websites. But without visiting every web page, that remaining number could contain any split between intentional an accident.

-SoundCloud has 83.3K domain feeds in Apple Podcast, and a smaller-than-I-expected-but-still-big 48.8K of those feeds have a Sound Cloud URL as the website.

-Anchor has 72,169 feeds in AP. All but 3 are pointing back to the podcast’s Anchor webpage and are not a podcast’s own branded website! (Edited by Request DJL)

He also looked at the total number of episodes across all feeds for the following companies an came up with these averages.

SoundCloud: 2,046,816 / average 24.5 episodes per show.
Libsyn: 1,980,221 / average 48.5 episodes per show.
Podbean: 789,113 / average 27.9 episodes per show.
Anchor  631,550 episodes /average of 8.8 episodes per show.
Spreaker: 613,082 / average 40.5 episodes per show.

There are some serious takeaways here we will update this article as he provides more data. Gives you some insight into what is really happening in the podcasting space.