What is the viscosity of francium?

Francium is a highly reactive alkali metal with a melting point of only 27°C. Due to its extreme rarity and radioactivity, very little research has been done on its physical properties such as viscosity. However, based on its position in the Periodic Table and the trends in atomic size and metallic character, it is likely to have a low viscosity similar to other alkali metals like cesium and potassium.