The lightbulb works fine...
Two. One to take out the bulb and drop it, and the other to try and sell it before it crashes.
None they'd rather keep their clients in the dark.
The people miss Harambe.
Claustrophobic
You command vast powers beyond the scope of smaller minds, but to them all you do is wiggle your fingers and stuff just happens.
A light bulb weighs about 50g and a single ant can lift about.2g, so it takes somewhere around 250 ants working together.
One Brazillion.
The answer may shock you.
Seven - one to actually change the bulb and six to complain that they liked the old one better.
N! One to change the light bulb, and n-1 to display stereotypical behavioral traits of X!
Medium Pizzas
Just one, but doing it will make them think they're going to be an electrician in the future.