256789 has 4 divisors (see below), whose sum is σ = 276556. Its totient is φ = 237024.

The previous prime is 256771. The next prime is 256799. The reversal of 256789 is 987652.

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

It can be written as a sum of positive squares in 2 ways, for example, as 54289 + 202500 = 233^2 + 450^2 .

It is a cyclic number.

It is not a de Polignac number, because 256789 - 2⁵ = 256757 is a prime.

It is a d-powerful number, because it can be written as 2¹⁷ + 5⁷ + 7³ + 6⁶ + 8³ + 9² .

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

It is a Duffinian number.

It is a plaindrome in base 10.

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 pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9864 + ... + 9889.

It is an arithmetic number, because the mean of its divisors is an integer number (69139).

2²⁵⁶⁷⁸⁹ is an apocalyptic number.

It is an amenable number.

256789 is a deficient number, since it is larger than the sum of its proper divisors (19767).

256789 is a wasteful number, since it uses less digits than its factorization.

256789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19766.

The product of its digits is 30240, while the sum is 37.

The square root of 256789 is about 506.7435248723. The cubic root of 256789 is about 63.5612074393.

The spelling of 256789 in words is "two hundred fifty-six thousand, seven hundred eighty-nine".