Played on a larger board of 21 squares by 21 squares, how many tiles are there in the game 'Super Scrabble'?

Introduced in 2004, 'Super Scrabble' is a variant of the board game 'Scrabble'. Traditionally, 'Scrabble' is played on a 15x15 grid with 100 tiles, but 'Super Scrabble' uses a 21×21 grid with twice as many letter tiles.

'Scrabble' is played by 2, 3 or 4 people, who take turns putting words on the board using any of the seven letters (tiles) that they have in front of them. Their word must connect to another word that is already on the board. 'Super Scrabble' follows the same rules, except there are more places on the board to lay down letters. Each letter has a number of points, with the less common letters being worth more points.

'Scrabble' was invented in 1938 by an architect named Alfred Mosher Butts. It later became a trademark of Hasbro in the US and Canada, although 'Super Scrabble' is manufactured by Mattel in other countries.