When any testator has authorized or directed any real property to be sold by his executors and has appointed several executors, part or all of whom for any cause have failed to act or have died before such sale or conveyance, and, when a sole executor so authorized to sell has failed to accept or has died and an administrator with the will annexed or de bonis non has been appointed to settle the estate, the acting or surviving executor or executors or the administrator shall have power to sell and convey such real property.