Sixtyseven

Sixty-seven is the natural number that follows sixty-six and precedes sixty-eight. In decimal notation it is written as 67. It is a prime number, meaning its only positive divisors are 1 and itself. Its representation across common numeral systems includes LXVII in Roman numerals, 0x43 in hexadecimal, 1000011 in binary, and 103 in octal. In ASCII, the decimal code 67 corresponds to the uppercase letter C.

Mathematics and number theory: As a prime, 67 is the 19th prime number. It is also listed among the Heegner numbers, a small set of positive integers associated with certain class number problems in imaginary quadratic fields.

Science and technology: Element 67 is Holmium (Ho), a lanthanide metal. Holmium has applications in magnets, specialized alloys, and certain glass formulations. It is relatively rare and occurs in minerals such as monazite and bastnäesite as part of natural rare-earth mixtures.

Culture and chronology: The year 1967 is a notable calendar year in modern history, associated with various cultural movements and political developments in many regions. The number 67 also appears in a variety of codes, designations, and identifiers across domains such as music, sports, and engineering, reflecting its role as a common numeric symbol.