256811 has 4 divisors (see below), whose sum is σ = 260712. Its totient is φ = 252912.

The previous prime is 256801. The next prime is 256813. The reversal of 256811 is 118652.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256811 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 (256813) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1850 + ... + 1983.

It is an arithmetic number, because the mean of its divisors is an integer number (65178).

2²⁵⁶⁸¹¹ is an apocalyptic number.

256811 is a deficient number, since it is larger than the sum of its proper divisors (3901).

256811 is an equidigital number, since it uses as much as digits as its factorization.

256811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3900.

The product of its digits is 480, while the sum is 23.

The square root of 256811 is about 506.7652316408. The cubic root of 256811 is about 63.5630225568.

The spelling of 256811 in words is "two hundred fifty-six thousand, eight hundred eleven".