Worth can be followed by a noun phrase which describes the value of something.

He died worth $20,000.
That piano is worth a few hundred dollars.
I don’t think their cakes are worth the money.
‘Shall I talk to Paul?’ ‘ It is not worth the trouble.’

In questions about the value of money what or how much can be used.

What is that piano worth? OR How much is that piano worth?

To talk about the value of an activity, we often use an -ing form with worth. Note that it is common to use it as a preparatory subject in these clauses.

It was worth meeting the manager. (NOT Meeting the manager is worth.)
It isn’t worth repairing that computer.
It isn’t worth talking to Peter.
Is it worth visiting Singapore?

Note that ideas such as these can also be expressed by a structure in which the object of the -ing form is made the subject of the sentence.

Peter is worth talking to. (= It is worth talking to Peter.)
That computer isn’t worth repairing. (NOT That computer isn’t worth repairing it.)
Is Singapore worth visiting? (NOT Is Singapore worth visiting it?)

In structures with -ing forms ‘worthwhile’ is sometimes used instead of worth.

Is it worthwhile visiting Singapore? (= Is it worth visiting Singapore?)

Worth can be modified by well.

The book is well worth reading. (NOT Reading the book is well worth.)