By looking at extreme spikes of Champernowne's constant and how well it's approximated by some rational numbers I think it's reasonable to think that this is a Liouville number. However, no source I could find answered the question. Is the answer known?
Thanks in advance!
The irrationality measure of the base $10$ Champernowne constant is $10$ (and similarly for other bases is the base).
The irrationality measure of Liouville numbers is infinite.
So a Champernowne constant is not a Liouville number.