THE answer is probably thousands of trillions of dollars at current (2016 A.D. based price estimates)

According to one estimate: http://waitbutwhy.com/2014/03/combined-wealth-world.html, the net worth the entire world is 241 trillion dollar.

If you check out the net GDP of the entire world in 2014, according to the CIA's World Factbook, the GWP totalled approximately US$107.5 trillion in terms of purchasing power parity (PPP), and around US$78.28 trillion in nominal terms.

When one considers the total real estate value of the 100 major cities in the world, with all their other wealths, it would probably cross 100 trillion.

E.g: The total value of real estate transaction in Manhattan is is roughly $750,000,000,000. Now, think of all the major cities in the world and their wealth!

Thus, if we can consider, on an average the net worth of each country in the world as say a few trillions, this itself would run in to hundreds of trillions for the entire world.

A single asteroid 100-mile wide Germania is worth about 100 trillion dollar as per the following link. If one could mine the mineral wealth in it, it is possible to gain so much worth.

Single asteroid worth £60 trillion if it was mined - as much as world earns in a year

Now, come to think of the minerals, crude oil, animal, herbal, wood, human, water, air, and all art, knowledge, cultural and many other forms of wealth in the world. That estimates has to be hundreds of trillions again.

Hence, to conclude, adding all the above, probably the wealth of the world should at least run into tens of thousands of trillions in dolllars at current 2016 price estimates!

A more accurate and realistic evaluation can be done by some deeply entrenched economist/finance expert only.

But despite calculations or estimates, the value of a place as unique and as habitable/suitable for life as Earth cannot be measured in terms of monetary value as no amount of money can buy us another Earth which is half as good!

What is the total net worth of the world?

HUUUGEEEEE