256406657 has 4 divisors (see below), whose sum is σ = 276130260. Its totient is φ = 236683056.

The previous prime is 256406639. The next prime is 256406663. The reversal of 256406657 is 756604652.

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

It can be written as a sum of positive squares in 2 ways, for example, as 83247376 + 173159281 = 9124^2 + 13159^2 .

It is a cyclic number.

It is not a de Polignac number, because 256406657 - 2²² = 252212353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256406617) 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, 9861782 + ... + 9861807.

It is an arithmetic number, because the mean of its divisors is an integer number (69032565).

Almost surely, 2^256406657 is an apocalyptic number.

It is an amenable number.

256406657 is a deficient number, since it is larger than the sum of its proper divisors (19723603).

256406657 is a wasteful number, since it uses less digits than its factorization.

256406657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19723602.

The product of its (nonzero) digits is 302400, while the sum is 41.

The square root of 256406657 is about 16012.7029885650. The cubic root of 256406657 is about 635.2964552889.

The spelling of 256406657 in words is "two hundred fifty-six million, four hundred six thousand, six hundred fifty-seven".