256791 has 4 divisors (see below), whose sum is σ = 342392. Its totient is φ = 171192.

The previous prime is 256771. The next prime is 256799. The reversal of 256791 is 197652.

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

It is not a de Polignac number, because 256791 - 2⁹ = 256279 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256799) 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, 42796 + ... + 42801.

It is an arithmetic number, because the mean of its divisors is an integer number (85598).

2²⁵⁶⁷⁹¹ is an apocalyptic number.

256791 is a deficient number, since it is larger than the sum of its proper divisors (85601).

256791 is an equidigital number, since it uses as much as digits as its factorization.

256791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85600.

The product of its digits is 3780, while the sum is 30.

The square root of 256791 is about 506.7454982533. The cubic root of 256791 is about 63.5613724542.

The spelling of 256791 in words is "two hundred fifty-six thousand, seven hundred ninety-one".