"Supercomputer" is a very vague name for a very powerful computer. If there were a more powerful type of computer than the ones you're thinking of, it would instantly be called a supercomputer.
Supercomputer
Supercomputer, to classify as such a system must have at least 10 times the performance of the highest performance conventional computers.
NORAD Supercomputer
They are fast, but a supercomputer is faster.
supercomputer is probably what you are looking for.
Talking biologically or technologically? MOST POWERFUL: Biologically, our brains are the most powerful "computer" in the world. It is highly developed and advanced. Technologically, there isn't a certain "most powerful" computer/laptop in the world. Companies like Dell, HP, or etc. are always coming out with new technology, so, who knows? LEAST POWERFUL: The least powerful? Well, probably the first computers every invented. At the time, they were considered powerful and useful, but now, since technology has improved so much, they are now considered useless. As for the most widely used type of computer...GOOGLE the statistics of the use of different types of computers.
These days, a large business computer with most of the space filled with disk drives, or a multiprocessor supercomputer with a billion or more CPUs,
the most powerful computers are called supercomputers and there able to do trillions of calculations per second the fastest computer is called the BlueGene/L and it can do 360 trillion calculations per second
The most expensive computer is made in Japan. It is an Earth simulator costing over $400,000,000, which makes it the most expensive computer ever built.This very expensive computer is used for a variety of international projects. Most are related to atmospheric, climate, and oceanographic simulation.
A supercomputer generates a lot of heat, so it needs air conditioning to compensate, otherwise it would overheat the room and burn itself up.
According to TOP500, the fastest computer is currently (as of September 2017) the Sunway TaihuLight, at a speed of 93 petaflops. I don't know whether this is also the most expensive computer.
It depends what type of computer you're talking about but the fastest computer in the world regardless of the type is China's Tianhe-2 supercomputer at 33.86 petaFLOPS, or 33.86 quadrillion floating point operations per second.