565

565 is a natural number that follows 564 and precedes 566. It is an odd composite number with prime factorization 5 × 113, so its divisors are 1, 5, 113, and 565.

In base-10, the digits form a palindrome, 565, which reads the same forward and backward. In Roman numerals it is DLXV. In other common bases it is 1000110101 in binary, 1065 in octal, and 0x235 in hexadecimal. The sum of its decimal digits is 16, so the number is not a Harshad number in base 10.

In the calendar context, the year 565 CE is notable for the accession of Justin II to the Byzantine throne, marking a transition in the Eastern Roman Empire. In optics, a wavelength of about 565 nanometers lies in the yellow-green portion of the visible spectrum.