256611911 has 2 divisors, whose sum is σ = 256611912. Its totient is φ = 256611910.

The previous prime is 256611899. The next prime is 256611913. The reversal of 256611911 is 119116652.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256611911 is a prime.

Together with 256611913, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256611913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128305955 + 128305956.

It is an arithmetic number, because the mean of its divisors is an integer number (128305956).

Almost surely, 2^256611911 is an apocalyptic number.

256611911 is a deficient number, since it is larger than the sum of its proper divisors (1).

256611911 is an equidigital number, since it uses as much as digits as its factorization.

256611911 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 32.

The square root of 256611911 is about 16019.1108055347. The cubic root of 256611911 is about 635.4659287356.

It can be divided in two parts, 25661 and 1911, that added together give a palindrome (27572).

The spelling of 256611911 in words is "two hundred fifty-six million, six hundred eleven thousand, nine hundred eleven".