Apart from Twitter’s built-in analytics, you must try the tool Followeraudit.
As Twitter analytics doesn’t provide a lot of stats that you can get from this tool such as
- Identify fake followers from your or any other public Twitter account.
- Identify inactive followers from your or any other public Twitter account.
- Track followers growth stats
- Track unfollowers
- Detailed followers analytics.
Most of these you won't get from the analytics tool of Twitter,
Hope you find it helpful.