This is the 3591st most frequent Polish word.
czterech
"Four" (genitive plural form in Polish).
The word 'czterech' is used as the numeral 'four' in genitive case, applied to the quantified noun 'braci' (brothers), as required by Polish grammar.
Mam czterech braci.
I have four brothers.
Here 'czterech' appears in the genitive case due to the negation of existence of the chairs, following Polish syntactic rules.
Nie ma czterech krzeseł w pokoju.
There are not four chairs in the room.
'Czterech' is in the accusative case, aligning with the verb 'zaproś' (invite) to indicate the number of people involved in the action.