Janitors are cleaners. Typically the people who maintain apartments are called maintenance workers, handymen, or (old fashioned) superintendent. Sometimes property manager, if they also handle renting it out.

Photogenic: Looks good in photographs; attractive

Memory: A construct of one's mind that allows them to recall information

a photogenic memory = a beautiful mind.

It is humorous because the assumption is that I mean to say "photographic memory". One with a photographic memory can recall visual information to which they've been exposed with great accuracy.

But when I tell this joke to friends or colleagues, I say "No no, a photogenic memory...I have a beautiful mind". There was a film with actor Russell Crowe called A Beautiful Mind in which he plays a brilliant professor who we discover late in the film has schizophrenia which has caused him no small amount of embarrassment and challenges in his life. According to diagnostic testing I had done, I have a high intelligence quotient along with autism, and it, too, has caused me embarrassment and challenges in my life.

So when I say I have a "beautiful mind", people remember that film and it occurs to them that I am saying I am intelligent (something friends and colleagues already know about me) but that my autism (something they also know about me) makes me a little weird and is a burden to me sometimes. It's just a bit of self-deprecating humor.

A photographic memory means you can recall a perfect visual image in your mind of a past event and examine it for details as if it were a picture. So, for example, if you are trying to remember a book quote, you'd bring up a visualization of the page of the book that you read and read the words on the page again.