256399911 has 20 divisors (see below), whose sum is σ = 383772312. Its totient is φ = 170596368.

The previous prime is 256399901. The next prime is 256399939. The reversal of 256399911 is 119993652.

It is a happy number.

256399911 is a `hidden beast` number, since 2 + 5 + 639 + 9 + 9 + 1 + 1 = 666.

256399911 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 256399911 - 2⁷ = 256399783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256399901) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 42276 + ... + 47958.

Almost surely, 2^256399911 is an apocalyptic number.

256399911 is a deficient number, since it is larger than the sum of its proper divisors (127372401).

256399911 is an equidigital number, since it uses as much as digits as its factorization.

256399911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6252 (or 6243 counting only the distinct ones).

The product of its digits is 131220, while the sum is 45.

The square root of 256399911 is about 16012.4923419185. The cubic root of 256399911 is about 635.2908837390.

It can be divided in two parts, 25 and 6399911, that added together give a palindrome (6399936).

The spelling of 256399911 in words is "two hundred fifty-six million, three hundred ninety-nine thousand, nine hundred eleven".