256643406 has 24 divisors (see below), whose sum is σ = 567893664. Its totient is φ = 83727360.

The previous prime is 256643381. The next prime is 256643419. The reversal of 256643406 is 604346652.

256643406 is a `hidden beast` number, since 2 + 5 + 6 + 643 + 4 + 0 + 6 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 150835 + ... + 152526.

It is an arithmetic number, because the mean of its divisors is an integer number (23662236).

Almost surely, 2^256643406 is an apocalyptic number.

256643406 is an abundant number, since it is smaller than the sum of its proper divisors (311250258).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256643406 is a wasteful number, since it uses less digits than its factorization.

256643406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303416 (or 303413 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

The square root of 256643406 is about 16020.0938199500. The cubic root of 256643406 is about 635.4919254253.

It can be divided in two parts, 256643 and 406, that added together give a square (257049 = 507²).

The spelling of 256643406 in words is "two hundred fifty-six million, six hundred forty-three thousand, four hundred six".