Project Euler and PowerShell - Problem 3

Problem 3 -The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143?

function isPrime
{
   param ($number)
   $isPrime = $true
   if($number -lt 2) { $isPrime = $False}
   if($number -gt 2 -and $number%2 -eq 0) {$isPrime = $False}
   for($i=3;$i -le [math]::Sqrt($number);$i+=2)
   {
       if($number % $i -eq 0) { $isPrime = $False}
   }   
   $isPrime
}   

$value=600851475143
$sqrValue =[Math]::Sqrt($value)

for($i=3;$i -le $sqrValue; $i+=2)
{
     if($value%$i -eq 0 -and (isPrime $i))
     {
           $maxPrime = $i
     }
}

$maxPrime