856811 has 2 divisors, whose sum is σ = 856812. Its totient is φ = 856810.

The previous prime is 856799. The next prime is 856813. The reversal of 856811 is 118658.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 856811 - 2¹⁰ = 855787 is a prime.

Together with 856813, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (856813) 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 as a sum of consecutive naturals, namely, 428405 + 428406.

It is an arithmetic number, because the mean of its divisors is an integer number (428406).

2⁸⁵⁶⁸¹¹ is an apocalyptic number.

856811 is a deficient number, since it is larger than the sum of its proper divisors (1).

856811 is an equidigital number, since it uses as much as digits as its factorization.

856811 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1920, while the sum is 29.

The square root of 856811 is about 925.6408590809. The cubic root of 856811 is about 94.9791644057.

The spelling of 856811 in words is "eight hundred fifty-six thousand, eight hundred eleven".