I have used CodeBlocks compiler for debugging purpose. But you can use any C++ programming language compiler as per your availability.

What is Armstrong number?

An Armstrong number is an n-digit number that is equal to the sum of the nth powers of its digits.

For Example: 407 = 43 + 03 + 73 = 64 + 0 + 343 = 407

#include <iostream>
#include <math.h>
 
using namespace std;
 
int main()
{
     int num, sum = 0, i, r;
    //Reading a number from user
    cout<<"Enter any number to calculate factorial:";
    cin>>num;
 
    //Finding armstrong number or not
    for(i = num; i>0; i=i/10)
    {
        r = i%10;
        sum = sum + r * r * r;
    }
     if ( num == sum ){
       cout<<num<<" is an armstrong number."<<endl;;
     }
    else{
        cout<<num<<" is not an armstrong number."<<endl;;
    }
 
    return 0;
}

Result:

Enter any number to calculate factorial:407

407 is an armstrong number.