256646605 has 8 divisors (see below), whose sum is σ = 308754072. Its totient is φ = 204798528.

The previous prime is 256646567. The next prime is 256646609. The reversal of 256646605 is 506646652.

It can be written as a sum of positive squares in 4 ways, for example, as 29571844 + 227074761 = 5438^2 + 15069^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 256646605 - 2²¹ = 254549453 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 (256646609) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62662 + ... + 66631.

It is an arithmetic number, because the mean of its divisors is an integer number (38594259).

Almost surely, 2^256646605 is an apocalyptic number.

It is an amenable number.

256646605 is a deficient number, since it is larger than the sum of its proper divisors (52107467).

256646605 is a wasteful number, since it uses less digits than its factorization.

256646605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129695.

The product of its (nonzero) digits is 259200, while the sum is 40.

The square root of 256646605 is about 16020.1936629992. The cubic root of 256646605 is about 635.4945658337.

The spelling of 256646605 in words is "two hundred fifty-six million, six hundred forty-six thousand, six hundred five".