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
Centered cube number can also be expressed as a trapezoidal number (difference of two triangular numbers), or a sum of consecutive numbers, as Because of the factorization formula_3, it is impossible for a centered cube number to be a prime number. The only centered cube number that is also a square number is 9. Centered cube number A centered cube number is a centered figurate number that counts the number of points in a three-dimensional pattern formed by a point surrounded by concentric cubical layers of points, with "i" points on the square faces of the "i"-th layer. Equivalently, it is the number