856738621 has 4 divisors (see below), whose sum is σ = 864745632. Its totient is φ = 848731612.

The previous prime is 856738609. The next prime is 856738639. The reversal of 856738621 is 126837658.

856738621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-856738621 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 (856738601) 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, 4003345 + ... + 4003558.

It is an arithmetic number, because the mean of its divisors is an integer number (216186408).

Almost surely, 2^856738621 is an apocalyptic number.

It is an amenable number.

856738621 is a deficient number, since it is larger than the sum of its proper divisors (8007011).

856738621 is a wasteful number, since it uses less digits than its factorization.

856738621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8007010.

The product of its digits is 483840, while the sum is 46.

The square root of 856738621 is about 29270.0977278860. The cubic root of 856738621 is about 949.7648987945.

The spelling of 856738621 in words is "eight hundred fifty-six million, seven hundred thirty-eight thousand, six hundred twenty-one".