256521 has 8 divisors (see below), whose sum is σ = 351424. Its totient is φ = 166320.

The previous prime is 256517. The next prime is 256541. The reversal of 256521 is 125652.

256521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 256521 - 2² = 256517 is a prime.

It is an Ulam number.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256541) 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, 1045 + ... + 1266.

It is an arithmetic number, because the mean of its divisors is an integer number (43928).

2²⁵⁶⁵²¹ is an apocalyptic number.

It is an amenable number.

256521 is a deficient number, since it is larger than the sum of its proper divisors (94903).

256521 is a wasteful number, since it uses less digits than its factorization.

256521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2351.

The product of its digits is 600, while the sum is 21.

The square root of 256521 is about 506.4790222704. The cubic root of 256521 is about 63.5390876794.

It can be divided in two parts, 256 and 521, that added together give a palindrome (777).

The spelling of 256521 in words is "two hundred fifty-six thousand, five hundred twenty-one".