Quite formidable.
And this was way before Viagra!
Muhammad had a similar situation, though "only" 4 wives. The Koran says that Allah gave him the stamina to "visit" all 4 of them every night.
That's kinda silly, but at the same time it's sad to think of all the Muslims holding up Muhammad's sexual perversion as a model -- especially with his favorite "wife" being the one who was 6-years-old.