856641439 has 4 divisors (see below), whose sum is σ = 858799624. Its totient is φ = 854483256.

The previous prime is 856641403. The next prime is 856641479. The reversal of 856641439 is 934146658.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 934146658 = 2 ⋅467073329.

It is a cyclic number.

It is not a de Polignac number, because 856641439 - 2⁷ = 856641311 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 (856641479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1078497 + ... + 1079290.

It is an arithmetic number, because the mean of its divisors is an integer number (214699906).

Almost surely, 2^856641439 is an apocalyptic number.

856641439 is a deficient number, since it is larger than the sum of its proper divisors (2158185).

856641439 is a wasteful number, since it uses less digits than its factorization.

856641439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2158184.

The product of its digits is 622080, while the sum is 46.

The square root of 856641439 is about 29268.4375906880. The cubic root of 856641439 is about 949.7289860356.

It can be divided in two parts, 8566 and 41439, that added together give a palindrome (50005).

The spelling of 856641439 in words is "eight hundred fifty-six million, six hundred forty-one thousand, four hundred thirty-nine".