High Quality Content by WIKIPEDIA articles! 6 (six) is the natural number following 5 and preceding 7. The SI prefix for 10006 is exa (E), and for its reciprocal atto (a). Six is the second smallest composite number, its proper divisors being 1, 2 and 3. Since six equals the sum of these proper divisors, six is the smallest perfect number. As a perfect number, 6 is related to the Mersenne prime 3, since 21(22 - 1) = 6. (The next perfect number is 28.) It is the only even perfect number that is not the sum of successive odd cubes. Being perfect six is the root of the 6-aliquot tree, and is itself the aliquot sum of only one number; the square number, 25. Unrelated to 6 being a perfect number, a Golomb ruler of length 6 is a "perfect ruler." S6, with 720 elements, is the only finite symmetric group which has an outer automorphism. This automorphism allows us to construct a number of exceptional mathematical objects such as the S(5,6,12) Steiner system, the projective plane of order 4 and the Hoffman-Singleton graph.

Данное издание не является оригинальным. Книга печатается по технологии принт-он-деманд после получения заказа.