256605493 has 4 divisors (see below), whose sum is σ = 256640140. Its totient is φ = 256570848.

The previous prime is 256605451. The next prime is 256605527. The reversal of 256605493 is 394506652.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 174847729 + 81757764 = 13223^2 + 9042^2 .

It is a cyclic number.

It is not a de Polignac number, because 256605493 - 2²⁵ = 223051061 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 (256605403) 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, 1230 + ... + 22687.

It is an arithmetic number, because the mean of its divisors is an integer number (64160035).

Almost surely, 2^256605493 is an apocalyptic number.

It is an amenable number.

256605493 is a deficient number, since it is larger than the sum of its proper divisors (34647).

256605493 is a wasteful number, since it uses less digits than its factorization.

256605493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34646.

The product of its (nonzero) digits is 194400, while the sum is 40.

The square root of 256605493 is about 16018.9104810533. The cubic root of 256605493 is about 635.4606309114.

The spelling of 256605493 in words is "two hundred fifty-six million, six hundred five thousand, four hundred ninety-three".