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
Radical of an integer of the multiples of formula_10. Radical of an integer In number theory, the radical of a positive integer "n" is defined as the product of the distinct prime numbers dividing "n". Each prime factor of "n" occurs exactly once as a factor of this product: The radical plays a central role in the statement of the abc conjecture. Radical numbers for the first few positive integers are For example, and therefore The function formula_4 is multiplicative (but not completely multiplicative). The radical of any integer "n" is the largest square-free divisor of "n" and so also described as the square-free