Manager::isAdmin

static function isAdmin()
{
	$user = self::getUserInstance();

	if (!($user instanceof CUser))
	{
		return false;
	}

	if (ModuleManager::isModuleInstalled('bitrix24'))
	{
		return $user->canDoOperation('bitrix24_config');
	}
	else
	{
		return $user->isAdmin();
	}
}