256355861 has 4 divisors (see below), whose sum is σ = 267501792. Its totient is φ = 245209932.

The previous prime is 256355851. The next prime is 256355863. The reversal of 256355861 is 168553652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256355861 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 (256355863) 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, 5572931 + ... + 5572976.

It is an arithmetic number, because the mean of its divisors is an integer number (66875448).

Almost surely, 2^256355861 is an apocalyptic number.

It is an amenable number.

256355861 is a deficient number, since it is larger than the sum of its proper divisors (11145931).

256355861 is a wasteful number, since it uses less digits than its factorization.

256355861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11145930.

The product of its digits is 216000, while the sum is 41.

The square root of 256355861 is about 16011.1167942777. The cubic root of 256355861 is about 635.2545002550.

The spelling of 256355861 in words is "two hundred fifty-six million, three hundred fifty-five thousand, eight hundred sixty-one".