856521 has 8 divisors (see below), whose sum is σ = 1268960. Its totient is φ = 570996.

The previous prime is 856519. The next prime is 856529. The reversal of 856521 is 125658.

856521 is a `hidden beast` number, since 8 + 5 + 652 + 1 = 666.

It is not a de Polignac number, because 856521 - 2¹ = 856519 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 31723 = 856521 / (8 + 5 + 6 + 5 + 2 + 1).

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (856529) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15835 + ... + 15888.

It is an arithmetic number, because the mean of its divisors is an integer number (158620).

2⁸⁵⁶⁵²¹ is an apocalyptic number.

It is an amenable number.

856521 is a deficient number, since it is larger than the sum of its proper divisors (412439).

856521 is a wasteful number, since it uses less digits than its factorization.

856521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31732 (or 31726 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 856521 is about 925.4841975960. The cubic root of 856521 is about 94.9684475087.

The spelling of 856521 in words is "eight hundred fifty-six thousand, five hundred twenty-one".