Apache has many security holes. It better to install and external firewall or a firewall software.

If you can pay, then I would say buy at least a cisco 505e firewall connected with the server externally.

or if you dont have/dont want to pay much in external ones. Use APF or CSF firewalls availble freely

I would recommend CSF which is priced at no cost. Its an idela solution if you have low budget or dont want to pa for external firewall. Also, it is still recommended for those who have external firewalls installed as they have a limited functionality.