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
Zeisel number additionally has prime factors with the relationship described above, so a name like Brown-Zeisel Numbers might be more appropriate. Hardy–Ramanujan's number 1729 is also a Zeisel number. Zeisel number A Zeisel number, named after Helmut Zeisel, is a square-free integer "k" with at least three prime factors which fall into the pattern where "a" and "b" are some integer constants and "x" is the index number of each prime factor in the factorization, sorted from lowest to highest. For the purpose of determining Zeisel numbers, formula_2. The first few Zeisel numbers are To give an example, 1729 is a Zeisel