857909 has 4 divisors (see below), whose sum is σ = 923916. Its totient is φ = 791904.

The previous prime is 857903. The next prime is 857929. The reversal of 857909 is 909758.

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

It can be written as a sum of positive squares in 2 ways, for example, as 372100 + 485809 = 610^2 + 697^2 .

It is a cyclic number.

It is not a de Polignac number, because 857909 - 2⁸ = 857653 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 (857903) 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, 32984 + ... + 33009.

It is an arithmetic number, because the mean of its divisors is an integer number (230979).

2⁸⁵⁷⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

857909 is a deficient number, since it is larger than the sum of its proper divisors (66007).

857909 is a wasteful number, since it uses less digits than its factorization.

857909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66006.

The product of its (nonzero) digits is 22680, while the sum is 38.

The square root of 857909 is about 926.2337717877. The cubic root of 857909 is about 95.0197188984.

The spelling of 857909 in words is "eight hundred fifty-seven thousand, nine hundred nine".