856779689 has 4 divisors (see below), whose sum is σ = 861219156. Its totient is φ = 852340224.

The previous prime is 856779653. The next prime is 856779691. The reversal of 856779689 is 986977658.

856779689 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 an emirpimes, since its reverse is a distinct semiprime: 986977658 = 2 ⋅493488829.

It can be written as a sum of positive squares in 2 ways, for example, as 419635225 + 437144464 = 20485^2 + 20908^2 .

It is a cyclic number.

It is not a de Polignac number, because 856779689 - 2⁸ = 856779433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (856779619) 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, 2219444 + ... + 2219829.

It is an arithmetic number, because the mean of its divisors is an integer number (215304789).

Almost surely, 2^856779689 is an apocalyptic number.

It is an amenable number.

856779689 is a deficient number, since it is larger than the sum of its proper divisors (4439467).

856779689 is a wasteful number, since it uses less digits than its factorization.

856779689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4439466.

The product of its digits is 45722880, while the sum is 65.

The square root of 856779689 is about 29270.7992545472. The cubic root of 856779689 is about 949.7800742987.

The spelling of 856779689 in words is "eight hundred fifty-six million, seven hundred seventy-nine thousand, six hundred eighty-nine".