Find the K-Beauty of a Number

<-E 2269> Find the K-Beauty of a Number

class Solution {
public:
    int divisorSubstrings(int num, int k) {
        string strAns = to_string(num);
        int n = strAns.size(),ans=0;
        for (int i = 0; i < (n-k+1); i++){
            if(stoi(strAns.substr(i, k)) != 0)
                if(!(num % stoi(strAns.substr(i, k))))
                    ans++;
        }
        return ans;
    }
};