Let \(d^{(k)}(n)\) be the k-free divisor function for integer \(k\ge 2\) . Let a be a nonzero integer. In this paper, we establish an asymptotic formula \(\begin{aligned} \sum _{p\le x} d^{(k)}(p-a) =b_k \cdot x+O\left( \frac{x}{\log x}\right) \end{aligned}\) related to the Titchmarsh divisor problem, where \(b_k\) is a positive constant dependent on k and a. For the proof, we apply a result of Felix and show a general asymptotic formula for a class of arithmetic functions including the unitary divisor function, k-free divisor function and the proper Pillai’s function.