How to check Armstrong number

An Armstrong number is a number that is the sum of the cubes of its digits is equal to the number itself.

Armstrong Number Logic:

xyz= (x*x*x) + (y*y*y) + (z*z*z)

Example: 0, 1, 153, 371, 407, 471, etc.

Armstrong Check Program Normal

<?php
$inputNumber=22;
$numSum = 0;   
$checkNumber = $inputNumber;   
while($checkNumber>0)   
{   
    $rem = $checkNumber % 10;   
    $numSum = $numSum + $rem*$rem*$rem;   
    $checkNumber = $checkNumber / 10;   
}

if ($inputNumber == $numSum) { 
    echo "$inputNumber is an Armstrong Number.";  
}else{  
    echo "$inputNumber is not an Armstrong Number.";  
}
?>

Output:

22 is not an Armstrong Number.

Armstrong Check Program Using Functions

<?php
function checkArmstrong($inputNumber=""){ 
	$numSum = 0;   
	$checkNumber = $inputNumber;   
	while($checkNumber>0)   
	{   
	    $rem = $checkNumber % 10;   
	    $numSum = $numSum + $rem*$rem*$rem;   
	    $checkNumber = $checkNumber / 10;   
	}

	if ($inputNumber == $numSum) { 
	    return true;  
	}else{  
	    return false;
	}
}
$inputNumber=371;
if (checkArmstrong($inputNumber)) { 
    echo "$inputNumber is an Armstrong Number.";  
}else{  
    echo "$inputNumber is not an Armstrong Number.";  
}
?>

Output:

371 is an Armstrong Number.