256355021 has 8 divisors (see below), whose sum is σ = 276199224. Its totient is φ = 236528640.

The previous prime is 256355009. The next prime is 256355023. The reversal of 256355021 is 120553652.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 52722121 + 203632900 = 7261^2 + 14270^2 .

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 256355021 - 2⁶ = 256354957 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 (256355023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51941 + ... + 56661.

It is an arithmetic number, because the mean of its divisors is an integer number (34524903).

Almost surely, 2^256355021 is an apocalyptic number.

It is an amenable number.

256355021 is a deficient number, since it is larger than the sum of its proper divisors (19844203).

256355021 is a wasteful number, since it uses less digits than its factorization.

256355021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8911.

The product of its (nonzero) digits is 9000, while the sum is 29.

The square root of 256355021 is about 16011.0905624820. The cubic root of 256355021 is about 635.2538064091.

The spelling of 256355021 in words is "two hundred fifty-six million, three hundred fifty-five thousand, twenty-one".