856404 has 18 divisors (see below), whose sum is σ = 2164890. Its totient is φ = 285456.

The previous prime is 856393. The next prime is 856411. The reversal of 856404 is 404658.

It can be written as a sum of positive squares in only one way, i.e., 608400 + 248004 = 780^2 + 498^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×856404² = 1466855622432, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

856404 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11859 + ... + 11930.

2⁸⁵⁶⁴⁰⁴ is an apocalyptic number.

It is an amenable number.

856404 is an abundant number, since it is smaller than the sum of its proper divisors (1308486).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

856404 is a wasteful number, since it uses less digits than its factorization.

856404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23799 (or 23794 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 856404 is about 925.4209852818. The cubic root of 856404 is about 94.9641231102.

The spelling of 856404 in words is "eight hundred fifty-six thousand, four hundred four".