Pascal IsPrime Function

function IsPrime(Number: Cardinal): Boolean;
var
  cDivisor,
  cMax : Cardinal;
begin
  Result := False;
  if Number and 1 = 0 then
    Exit;
  cMax := Trunc(Sqrt(Number)) + 1;
  cDivisor := 3;
  while cMax > cDivisor do begin
    if Number mod cDivisor = 0 then
      Exit;
    Inc(cDivisor, 2);
    if Number mod cDivisor = 0 then
      Exit;
    Inc(cDivisor, 4);
  end;
  Result := True;
end;