Agent Zero says Russell Westbrook can have #0 in D.C. if he wants it ... 'cause Gilbert Arenas is giving his official blessing to let the new Wizards star wear his old number.
Russ was traded to Washington in a swap with John Wall earlier this week ... and the team introduced Brodie on social media with edited pics of the guard wearing a #4 jersey (the same digit he wore in high school).
So ... why change from the number he had his whole NBA career?