256399013 has 4 divisors (see below), whose sum is σ = 276122028. Its totient is φ = 236676000.

The previous prime is 256399007. The next prime is 256399019. The reversal of 256399013 is 310993652.

256399013 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is an interprime number because it is at equal distance from previous prime (256399007) and next prime (256399019).

It can be written as a sum of positive squares in 2 ways, for example, as 72471169 + 183927844 = 8513^2 + 13562^2 .

It is a cyclic number.

It is not a de Polignac number, because 256399013 - 2⁸ = 256398757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256399019) 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, 9861488 + ... + 9861513.

It is an arithmetic number, because the mean of its divisors is an integer number (69030507).

Almost surely, 2^256399013 is an apocalyptic number.

It is an amenable number.

256399013 is a deficient number, since it is larger than the sum of its proper divisors (19723015).

256399013 is a wasteful number, since it uses less digits than its factorization.

256399013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19723014.

The product of its (nonzero) digits is 43740, while the sum is 38.

The square root of 256399013 is about 16012.4643012873. The cubic root of 256399013 is about 635.2901420696.

The spelling of 256399013 in words is "two hundred fifty-six million, three hundred ninety-nine thousand, thirteen".