64 (number) 64 (number) 64 (sixty-four) is the natural number following 63 and preceding 65. Sixty-four is the square of 8, the cube of 4, and the sixth power of 2. It is the smallest number with exactly seven divisors. It is the lowest positive power of two that is adjacent to neither a Mersenne prime nor a Fermat prime. 64 is the sum of Euler's totient function for the first fourteen integers. It is also a dodecagonal number and a centered triangular number. 64 is also the first whole number that is both a perfect square and a perfect cube. Since
26 (number) 26 (number) 26 (twenty-six) is the natural number following 25 and preceding 27. 26 is the only integer that is one greater than a square (5 + 1) and one less than a cube (3 − 1). A rhombicuboctahedron has twenty-six faces. When a 3 × 3 × 3 cube is made of twenty-seven unit cubes, twenty-six of them are viewable as the exterior layer. There are 26 sporadic groups. The 26-dimensional Lorentzian unimodular lattice II plays a significant role in sphere packing problems and the classification of finite simple groups. In particular, the Leech lattice is obtained in a