Code::Blocks 13.12 C++ sum of integers giving wrong answer

just now I wrote a simple function in C++ that determines if a number is narcissistic or not, and I have stumbled upon something most peculiar. I get the wrong sum in function "IsNumberNarcissistic" for numbers 9800817 and 9926315, which are both narcissistic. The sum I get is always 1 less than it should be, that is 9800816 and 9926314 for these numbers respectively. However, declaring the variable sum as a double solves the problem.

So my question is, what is going on here? Is it Code:Blocks related problem, or something else? I'm using Code:Blocks 13.12. Thank you in advance.

PS. Don't mind those prints I made in the function, I just put them there to see the variable values.

    #include <iostream>
    #include <vector>
    #include <cmath>
    #include <iomanip>

    using std::cin; using std::cout; using std::endl;

    std::vector<int> extractDigits(int n)
    {
        std::vector<int> digits;
        while (n>0)
        {
            digits.push_back(n%10);
            n/=10;
        }
        return digits;
    }

    bool IsNumberNarcissistic(int n)
    {
        auto digits = extractDigits(n);
        int sum(0);
        int power = digits.size();
        for (int digit : digits) sum += std::pow(digit, power);
        for (int digit : digits) cout << std::setprecision(10)     
        << std::pow(digit, power) << endl;
        cout << endl << endl << sum;
        return (sum == n);
    }

    int main()
    {
        IsNumberNarcissistic(9800817);
    }