C Program to check abundant number

In this tutorial, we will write a C program to check if a number is abundant number or not. A number is called an abundant number if sum of its proper divisors (excluding itself) is greater than the number itself.

Note: Proper divisors are numbers that divide the given number without leaving a remainder.

For example: Let’s check whether number 12 is abundant or not. Proper divisors of 12 are 1, 2, 3, 4, and 6. The sum of these proper divisors is 1 + 2 + 3 + 4 + 6 = 16. Since the sum of proper divisors (16) is greater than the number itself (12). Thus, we can say that 12 is an abundant number.

C Program to check if a number is abundant or not

#include <stdio.h>

int isAbundant(int num) {
    int sum = 0;
    
    // Calculate the sum of proper divisors
    for (int i = 1; i <= num / 2; i++) {
        if (num % i == 0) {
            sum += i;
        }
    }
    
    // Check if the sum of proper divisors is greater than the number
    return sum > num;
}

int main() {
    int num;

    // Input number from user
    printf("Enter a number: ");
    scanf("%d", &num);

    // Check if the number is an abundant number
    if (isAbundant(num)) {
        printf("%d is an abundant number.\n", num);
    } else {
        printf("%d is not an abundant number.\n", num);
    }

    return 0;
}

The function isAbundant() takes integer number as argument and returns 1 if the number is abundant else it returns 0.

In this function, a for loop finds the proper divisors and add those to the variable sum. Then, it compares this sum with the number itself to determine if it’s abundant or not

Output:

Output 1:

Enter a number: 12
12 is an abundant number.

Output 2:

Enter a number: 7
7 is not an abundant number.