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.

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