Eightyone

Eightyone is most commonly a representation of the decimal number 81. It is also used as a proper name or brand, with some entities stylizing the term as EightyOne.

As a number, 81 has several notable mathematical properties. It equals 3 to the fourth power (3^4), making it both a perfect fourth power and a perfect square (9^2). It is odd and composite, with positive divisors of 1, 3, 9, 27, and 81. In different numeral systems, 81 appears in several characteristic forms: in base 3 it is 10000, in base 9 it is 100, in base 8 it is 121, and in binary it is 1010001. In Roman numerals, 81 is written as LXXXI.

In science, 81 denotes the atomic number of thallium, a soft post-transition metal with a history of varied uses in electronics and optics. Because thallium is highly toxic, many traditional applications have been restricted or phased out in favor of safer materials.

In culture and commerce, the term eightyone is sometimes used as a brand name, product line, venue name, or stylistic choice in titles and marketing. Its use as a proper noun varies by region and industry, often chosen for branding or numerical symbolism rather than signifying a specific, universal meaning.

See also: 81 (disambiguation) for additional contexts and uses of the number 81.