What's the smallest amount you can retire on?

[nun]

I'm interested to know the smallest annual income folks have retired on. I'm assuming that the big ticket items are paid for, ie. you've paid off the mortgage so that the only housing expense is taxes and repairs and you have no car payments. I'm single, 46, and excluding my mortgage, my annual expenses are
$24k so I calculate that I can think about retiring once I have $750k saved and the mortgage paid off. What do you think?