256863865 has 4 divisors (see below), whose sum is σ = 308236644. Its totient is φ = 205491088.

The previous prime is 256863853. The next prime is 256863889. The reversal of 256863865 is 568368652.

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 116014441 + 140849424 = 10771^2 + 11868^2 .

It is a cyclic number.

It is not a de Polignac number, because 256863865 - 2¹³ = 256855673 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25686382 + ... + 25686391.

It is an arithmetic number, because the mean of its divisors is an integer number (77059161).

Almost surely, 2^256863865 is an apocalyptic number.

It is an amenable number.

256863865 is a deficient number, since it is larger than the sum of its proper divisors (51372779).

256863865 is an equidigital number, since it uses as much as digits as its factorization.

256863865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51372778.

The product of its digits is 2073600, while the sum is 49.

The square root of 256863865 is about 16026.9730454631. The cubic root of 256863865 is about 635.6738377786.

The spelling of 256863865 in words is "two hundred fifty-six million, eight hundred sixty-three thousand, eight hundred sixty-five".