256321 has 4 divisors (see below), whose sum is σ = 276052. Its totient is φ = 236592.

The previous prime is 256313. The next prime is 256337. The reversal of 256321 is 123652.

It is a happy number.

256321 is nontrivially palindromic in base 12.

256321 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 25921 + 230400 = 161^2 + 480^2 .

It is a cyclic number.

It is not a de Polignac number, because 256321 - 2³ = 256313 is a prime.

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 (256301) 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, 9846 + ... + 9871.

It is an arithmetic number, because the mean of its divisors is an integer number (69013).

2²⁵⁶³²¹ is an apocalyptic number.

It is an amenable number.

256321 is a deficient number, since it is larger than the sum of its proper divisors (19731).

256321 is a wasteful number, since it uses less digits than its factorization.

256321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19730.

The product of its digits is 360, while the sum is 19.

The square root of 256321 is about 506.2815422272. The cubic root of 256321 is about 63.5225703552.

Adding to 256321 its reverse (123652), we get a palindrome (379973).

The spelling of 256321 in words is "two hundred fifty-six thousand, three hundred twenty-one".