64 (number) it is possible to find sequences of 64 consecutive integers such that each inner member shares a factor with either the first or the last member, 64 is an Erdős–Woods number. In base 10, no integer added up to its own digits yields 64, hence it is a self number. 64 is a superperfect number—a number such that σ(σ("n")) = 2"n". 64 is the index of Graham's number in the rapidly growing sequence 3↑↑↑↑3, 3 ↑ 3,… Sixty-four is: 64 (number) 64 (sixty-four) is the natural number following 63 and preceding 65. Sixty-four is the square of 8, the cube
Square-free integer square-free factors that are naturally associated to every integer: the square-free part, the above factor , and the largest square-free factor. Each is a factor of the next one. All are easily deduced from a prime factorization: if is the prime factorization of , where formula_3 are distinct prime numbers, then the square-free part is The square-free factor such the quotient is a square is and the largest square-free factor is For example, if formula_7 the square-free part is , the square-free factor such that the quotient is a square is , and the largest square-free factor is . No