856445009 has 4 divisors (see below), whose sum is σ = 978794304. Its totient is φ = 734095716.

The previous prime is 856444999. The next prime is 856445021. The reversal of 856445009 is 900544658.

It is a happy number.

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 not a de Polignac number, because 856445009 - 2²⁰ = 855396433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (856445059) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61174637 + ... + 61174650.

It is an arithmetic number, because the mean of its divisors is an integer number (244698576).

Almost surely, 2^856445009 is an apocalyptic number.

It is an amenable number.

856445009 is a deficient number, since it is larger than the sum of its proper divisors (122349295).

856445009 is a wasteful number, since it uses less digits than its factorization.

856445009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122349294.

The product of its (nonzero) digits is 172800, while the sum is 41.

The square root of 856445009 is about 29265.0817357478. The cubic root of 856445009 is about 949.6563887515.

The spelling of 856445009 in words is "eight hundred fifty-six million, four hundred forty-five thousand, nine".