How can a man go eight days without sleep?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

I cannot talk, but I always reply when spoken to. What am I?

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

It was a dark stormy night and a couple were in a car driving madly to a city. The car broke down and the husband had to go get help from someone who spoke his language. He was afraid to leave his wife alone in the car so he locked the car before leaving. When he came back, the car was in the same state as he had left it but his wife was dead, there was blood on the floor and there was a stranger in the car. What happened?

He runs but never walks. Murmurs, but never talks. Has a bed, but never sleeps. And has a mouth, but never eats?

You have an empty wine bottle with a cork that has been secured at the top in a normal way. There is a metal ring inside the bottle that is suspended by a string.

How can you make the metal ring drop to the bottom if you are not allowed to touch anything - not the bottle, not the cork, not the thread and not the ring?

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?