Martin Dúbravka’s shirt number at Spurs has not been clearly confirmed in the sources I found, so the safest answer is that it’s still TBD for now. He has been confirmed as joining Tottenham from Burnley, but the publicly available transfer coverage I found does not state a squad number.

What’s known

  • Tottenham have confirmed the signing.
  • The player profile now lists him as a Tottenham Hotspur goalkeeper.
  • No reliable source in the results I found gives an official shirt number yet.

Practical read

Clubs often finalize or announce shirt numbers closer to registration or squad updates, so the number may appear after the move is fully processed. For the moment, the best answer is: not announced yet.

TL;DR: Martin Dúbravka’s Spurs number hasn’t been officially published in the sources I checked, so it’s currently unconfirmed.