256561111 has 4 divisors (see below), whose sum is σ = 259808800. Its totient is φ = 253313424.

The previous prime is 256561099. The next prime is 256561117. The reversal of 256561111 is 111165652.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 256561111 - 2¹⁵ = 256528343 is a prime.

It is a super-3 number, since 3×256561111³ (a number of 26 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 256561111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256561117) by changing a digit.

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, 1623726 + ... + 1623883.

It is an arithmetic number, because the mean of its divisors is an integer number (64952200).

Almost surely, 2^256561111 is an apocalyptic number.

256561111 is a deficient number, since it is larger than the sum of its proper divisors (3247689).

256561111 is an equidigital number, since it uses as much as digits as its factorization.

256561111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3247688.

The product of its digits is 1800, while the sum is 28.

The square root of 256561111 is about 16017.5251209417. The cubic root of 256561111 is about 635.4239927767.

The spelling of 256561111 in words is "two hundred fifty-six million, five hundred sixty-one thousand, one hundred eleven".