856405 has 16 divisors (see below), whose sum is σ = 1171584. Its totient is φ = 594880.

The previous prime is 856393. The next prime is 856411. The reversal of 856405 is 504658.

It is not a de Polignac number, because 856405 - 2⁷ = 856277 is a prime.

It is a Duffinian number.

856405 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 927 + ... + 1603.

It is an arithmetic number, because the mean of its divisors is an integer number (73224).

2⁸⁵⁶⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

856405 is a deficient number, since it is larger than the sum of its proper divisors (315179).

856405 is a wasteful number, since it uses less digits than its factorization.

856405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 716.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 856405 is about 925.4215255763. The cubic root of 856405 is about 94.9641600725.

The spelling of 856405 in words is "eight hundred fifty-six thousand, four hundred five".