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 integer between "x" and formula_26 for positive "x". Moreover, an elementary argument allows us to replace formula_26 by formula_28. The ABC conjecture would allow formula_29. If we represent a square-free number as the infinite product then we may take those formula_31 and use them as bits in a binary number with the encoding The square-free number 42 has factorization 2 × 3 × 7, or as an infinite product 2 · 3 · 5 · 7 · 11 · 13 ··· Thus the number 42 may be encoded as the binary sequence ...001011 or 11 decimal. (Note that the