As far as calendars are concerned, I can recommend
It's easy to install, use and configure. Additionally, it offers fully functional synchronization for many online calendar services, e.g. Google Calendar, which would be the calendar synchronization option of choice when it comes to Android, wouldn't it?
I'm using Rainlendar since ms windows times and it never failed me. I'm using it to sync my android phone and ubuntu calendars every day. It's the best calendar application on linux I've been able to find so far.
If you want to synchronize calendars offline, as I suppose judging from your question, then you can e.g. download your calendar file as ics-file and import it to Rainlendar as well.