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
The Cube Root of Uncertainty The Cube Root of Uncertainty The Cube Root of Uncertainty is a collection of science fiction short stories by American writer Robert Silverberg, published in hardcover by Macmillan in 1970 and issued in paperback by Collier Books in 1971. No further editions have been issued. "Passengers" won the Nebula Award for Best Short Story and was nominated for the Hugo Award. Joanna Russ gave the collection a mixed review, noting its division between early work ("Old Silverberg is an idiot") and more recent efforts ("New Silverberg is something else: a highly colored, gloomy, melodramatic, morally allegorical writer who luxuriates in