For how many days do the two witnesses prophesy, clothed in sackcloth?

Answer: 1,260

"I will empower my two witnesses, and they will prophesy for 1,260 days, clothed in sackcloth."

“And I will empower my two witnesses, and they will prophesy for 1,260 days, clothed in sackcloth.””— Revelation 11:3 (BSB)