This is a tricky question, as it depends on what "Apollo" you're referring to.

* Apollo missions overall: Apollo missions 11 through 17 landed on the moon (Apollo 13 had to abort). The total time spent on the lunar surface by all the missions combined was over 300 hours, or roughly 12.5 days.

* Each individual mission: Each Apollo mission stayed on the moon for a different amount of time, ranging from about 21.5 hours (Apollo 11) to 75 hours (Apollo 17).

So, to be more specific, you'll need to specify which Apollo mission you're interested in.