From [this answer](https://crypto.stackexchange.com/a/65968/51525), I see that from a mathematical point of view, one could define the $\text{Keccak-}f[25w]$ permutation for an arbitrary value of $w$.  
  
I am interested in the following question: disregarding all properties of the resulting function except the invertibility (because $\text{Keccak-}f[25w]$ is required to be a permutation), is it true that if the value of $w$ is a multiple of $8$ and not a multiple of $5$, the corresponding $\text{Keccak-}f[25w]$ function is invertible (and [bijective](https://en.wikipedia.org/wiki/Bijection))? If not, how to determine whether a particular $w$ is suitable (assuming that $w$ is required to be a multiple of $8$)?