Code tham khảo

bool isPrime(long long n){
    for (long long i = 2; i * i <= n; ++i)
        if (n % i == 0) return false;
    return n >= 2;
}

long long calc(long long n){
    long long res = 0;
    while (n){
        res += (n % 10) * (n % 10);
        n /= 10;
    }
    return res;
}

void solve(){
    long long n; cin >> n;
    long long tmp = calc(n);
    if (isPrime(tmp)) cout << 1; else cout << -1; 
    cout << '\n' << tmp;
}