What does this Rebus Picture means ?

What is next number in the pattern below:

131 517 192 123 ?

What is the fastest way to double your money?

In a town, there are over 100 flats.
Flat-1 is named first flat.
Flat-2 is named second flat.
Flat-3 is named third flat.

A visitors 'Victor' decides to walk through all the flats, he finds all the flats except flat-62.
Victor later founds that the local of the town have given it another name.

What is the name of the Flat?

What is the longest word in the dictionary?

What always comes into a house through the keyhole?

Solve the riddle below:

If a Chicken says, 'All chickens are liars" is the chicken telling the truth?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

There are two insects on a tile. Insect X is sitting on one side of the tile (point A) and Insect Y is sitting opposite on the other side of the tile (point B). Now both of them decide to change their position and thus X starts crawling to point B and Y starts crawling to point A. When they meet and pass each other in between, X takes 20 seconds to reach B and Y takes just 5 seconds to reach A.

Can you calculate the total time each of the insects took to change their positions?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?