256406 has 4 divisors (see below), whose sum is σ = 384612. Its totient is φ = 128202.

The previous prime is 256393. The next prime is 256423. The reversal of 256406 is 604652.

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

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 256406.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64100 + ... + 64103.

It is an arithmetic number, because the mean of its divisors is an integer number (96153).

2²⁵⁶⁴⁰⁶ is an apocalyptic number.

256406 is a deficient number, since it is larger than the sum of its proper divisors (128206).

256406 is a wasteful number, since it uses less digits than its factorization.

256406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128205.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 256406 is about 506.3654806560. The cubic root of 256406 is about 63.5295912674.

The spelling of 256406 in words is "two hundred fifty-six thousand, four hundred six".