664882391 has 4 divisors (see below), whose sum is σ = 687809400. Its totient is φ = 641955384.

The previous prime is 664882381. The next prime is 664882397. The reversal of 664882391 is 193288466.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 664882391 - 2¹⁰ = 664881367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664882397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11463461 + ... + 11463518.

It is an arithmetic number, because the mean of its divisors is an integer number (171952350).

Almost surely, 2^664882391 is an apocalyptic number.

664882391 is a deficient number, since it is larger than the sum of its proper divisors (22927009).

664882391 is a wasteful number, since it uses less digits than its factorization.

664882391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22927008.

The product of its digits is 497664, while the sum is 47.

The square root of 664882391 is about 25785.3134749221. The cubic root of 664882391 is about 872.8004142262.

The spelling of 664882391 in words is "six hundred sixty-four million, eight hundred eighty-two thousand, three hundred ninety-one".