Yes, PRESIDENTS is a Scrabble word!

Letter values in Scrabble US: P 3, R 1, E 1, S 1, I 1, D 2, E 1, N 1, T 1, S 1.

Is it a valid word?

PRESIDENTS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an executive officer of a firm or corporation
the person who holds the office of head of state of the United States government
the chief executive of a republic
the officer who presides at the meetings of an organization
the head administrative officer of a college or university
the office of the United States head of state

Also: president of the united states, united states president, chief executive.