It is a purple-black crystalline solid. It can dissolve in water to make a bright pink solution. It dissolves in water more than potassium permanganate. It is more expensive than potassium permanganate. It also absorbs water from the air. It is a strong oxidizing agent.
It cannot be made in the way that potassium permanganate is made because sodium manganate is not made. It can be made by reacting pure manganese(IV) oxide with sodium hypochlorite. It can also be made by reacting potassium permanganate with certain sodium compounds.
It can be used to make circuit boards.
Permanganates are toxic. They are also strong oxidizing agents and should be kept away from things that can burn.