Sometimes it's useful to connect to a computer via Teamviewer, although you're able to reach it via file sharing and you have complete access to the local machine file system of the main disk. You need just to check inside the following path:

\\network_path\c$\Program Files (x86)\TeamViewer\Version9

Now please open the contained log file:

TeamViewer9_Logfile.log

If you look at the beginning of the file, you may find some handshaking between the application and one of the TeamViewer servers to determine its own TeamViewer ID. There will be a line stating that a new RSA key pair has been generated. The following lines should contain somewhere the ID just after the From= string. That's the TeamViewer ID just assigned from the TeamViewer servers.

2017/07/25 13:50:25.295 2920 1516 S0 Generating new RSA private/public key pair
2017/07/25 13:50:25.342 2920 1516 S0 CT4 CT.Send.CMD_MASTERCOMMAND From=123456789 To=0 L=310

You may confirm that number is right looking at following lines where somebody initiated a TeamViewer connection to your machine:

2017/07/25 13:57:40.511 2148 4008 S0 CT4 CT.Receive.CMD_ROUTERCMD From=987654321 To=123456789 L=1835

In this log file there's plenty of occurrences of that number in several queries. That's enough for you to detect the TeamViewer ID. Now it's up to you to find the password by yourself!