256385421 has 6 divisors (see below), whose sum is σ = 370334510. Its totient is φ = 170923608.

The previous prime is 256385413. The next prime is 256385447. The reversal of 256385421 is 124583652.

256385421 is a `hidden beast` number, since 256 + 385 + 4 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 246929796 + 9455625 = 15714^2 + 3075^2 .

It is not a de Polignac number, because 256385421 - 2³ = 256385413 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 (256385401) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14243626 + ... + 14243643.

Almost surely, 2^256385421 is an apocalyptic number.

It is an amenable number.

256385421 is a deficient number, since it is larger than the sum of its proper divisors (113949089).

256385421 is a wasteful number, since it uses less digits than its factorization.

256385421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28487275 (or 28487272 counting only the distinct ones).

The product of its digits is 57600, while the sum is 36.

The square root of 256385421 is about 16012.0398762931. The cubic root of 256385421 is about 635.2789160563.

The spelling of 256385421 in words is "two hundred fifty-six million, three hundred eighty-five thousand, four hundred twenty-one".