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
Squaring the square squaring the square: that is, given a cube "C", the problem of dividing it into finitely many smaller cubes, no two congruent. Unlike the case of squaring the square, a hard yet solvable problem, there is no perfect cubed cube and, more generally, no dissection of a rectangular cuboid "C" into a finite number of unequal cubes. Suppose that there is such a dissection. Make a face of "C" its horizontal base. The base is divided into a perfect squared rectangle "R" by the cubes which rest on it. Each corner square of "R" has a smaller adjacent edge square,