256557221 has 8 divisors (see below), whose sum is σ = 263777184. Its totient is φ = 249394320.

The previous prime is 256557199. The next prime is 256557239. The reversal of 256557221 is 122755652.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256557221 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256457221) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 5066 + ... + 23211.

It is an arithmetic number, because the mean of its divisors is an integer number (32972148).

Almost surely, 2^256557221 is an apocalyptic number.

It is an amenable number.

256557221 is a deficient number, since it is larger than the sum of its proper divisors (7219963).

256557221 is a wasteful number, since it uses less digits than its factorization.

256557221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28531.

The product of its digits is 42000, while the sum is 35.

The square root of 256557221 is about 16017.4036909856. The cubic root of 256557221 is about 635.4207813107.

The spelling of 256557221 in words is "two hundred fifty-six million, five hundred fifty-seven thousand, two hundred twenty-one".