Filter and str.isdigit producing an error

[tester_V]

Greetings!
It is probably an elementary problem for you but I'm struggling to understand why the snippet below is failing.
I found it online and it looks ok, but it is not.

s = 'November 11 day' 
pp = int(filter(str.isdigit, s))
print(f" Digits only  -> {pp}")

error:
"int() argument must be a string, a bytes-like object or a number, not 'filter'"

if anyone would explain to me why it errors out...
Thank you!