/etc/sudoers is owned by uid 33, should be 0 [duplicate]

when I try to use sudo -I command, I get this error:

sudo: /etc/sudoers is owned by uid 33, should be 0
sudo: no valid sudoers sources found, quitting
sudo: unable to initialize policy plugin

so I tried to use pkexec chown -R root:root /etc/sudoers and I get this error:

polkit-agent-helper-1: error response to PolicyKit daemon: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: No session for cookie
==== AUTHENTICATION FAILED ===
Error executing command as another user: Not authorized
This incident has been reported.

Does anyone know what to do with this?

EDIT:

I think it is because I ran sudo chown www-data:www-data / by a mistake, but I stopped it after few seconds.

What do you think, I should do with that?