591

591 is a natural number that comes after 590 and before 592. In mathematics it is an odd composite number with prime factorization 3 × 197. Its divisors are 1, 3, 197, and 591.

In numeral representations, 591 is written as 1001001111 in binary and 0x24F in hexadecimal. In Roman numerals it is DXCI.

In color and optics, light with a wavelength near 591 nanometers lies in the yellow–orange region of the visible spectrum.

In telecommunications, the international dialing code for Bolivia is +591.

As a calendar year, 591 CE and 591 BCE appear in historical chronology for various regions, with events and contexts that differ across cultures and time periods.