PHP Program to Check Amicable Number

Posted in PHP Tutorial

Updated on Oct 31, 2024

By Mari Selvan

👁️ 41 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, exploring number properties is a fascinating journey. One interesting concept is that of amicable numbers.

Amicable numbers are two numbers that share a unique relationship: the sum of the proper divisors of each number is equal to the other number.

In simpler terms, the sum of the divisors of one number is the other number itself.

In this tutorial, we'll dive into a PHP program designed to check whether two given numbers are amicable or not.

The program will identify and compare the sum of proper divisors to determine if the numbers form an amicable pair.

📄 Example

Let's take a look at the PHP code that accomplishes this task.

areAmicable.php

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<?php
// Function to calculate the sum of proper divisors of a number
function sumOfDivisors($num)
{
  $sum = 1; // Start with 1 as every number is divisible by 1
  for ($i = 2;$i * $i <= $num;++$i)
  {
    if ($num % $i == 0)
    {
      $sum += $i;
      if ($i != $num / $i)
      {
        $sum += $num / $i;
      }
    }
  }

  return $sum;
}

// Function to check if two numbers are amicable
function areAmicable($num1, $num2)
{
  return sumOfDivisors($num1) == $num2 && sumOfDivisors($num2) == $num1;
}

// Replace these values with your desired numbers
$number1 = 220;
$number2 = 284;

// Check if the numbers are amicable
if (areAmicable($number1, $number2))
{
  echo "$number1 and $number2 are amicable numbers.\n";
}
else
{
  echo "$number1 and $number2 are not amicable numbers.\n";
}

?>

💻 Testing the Program

To test the program with different numbers, replace the values of $number1 and $number2 in the code.

Output

220 and 284 are amicable numbers.

Run the script to check if the numbers form an amicable pair.

🧠 How the Program Works

The program defines a function sumOfDivisors to calculate the sum of proper divisors for a given number.
Another function, areAmicable, checks whether two numbers are amicable by comparing the sums of their proper divisors.
The main part of the script tests the amicability of two numbers and prints the result.

🧐 Understanding the Concept of Amicable Numbers

Amicable numbers exhibit a unique relationship where the sum of the proper divisors of each number is equal to the other number.

For example, the pair (220, 284) is amicable because the sum of divisors of 220 is 284, and the sum of divisors of 284 is 220.

🎢 Optimizing the Program

While the provided program is effective, you may explore optimizations such as caching the results of the sum of divisors to enhance performance for repeated calculations.

Feel free to incorporate and modify this code as needed for your specific use case. Happy coding!