What are the features of the world's 'most powerful missile' tested by Russia?

Russia has successfully tested the Sarmat intercontinental ballistic missile, which Russia's Defence Ministry called the world's "most powerful missile". It weighs more than 200 tonnes and is able to transport multiple warheads. As per Russian media, Sarmat is a three-stage, liquid-fueled missile with a range of 18,000 km. It has been designed to elude anti-missile defence systems.