556520221 has 4 divisors (see below), whose sum is σ = 557165952. Its totient is φ = 555874492.

The previous prime is 556520149. The next prime is 556520243. The reversal of 556520221 is 122025655.

556520221 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 556520221 - 2²¹ = 554423069 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 556520221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (556520281) 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, 321571 + ... + 323296.

It is an arithmetic number, because the mean of its divisors is an integer number (139291488).

Almost surely, 2^556520221 is an apocalyptic number.

It is an amenable number.

556520221 is a deficient number, since it is larger than the sum of its proper divisors (645731).

556520221 is an equidigital number, since it uses as much as digits as its factorization.

556520221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 645730.

The product of its (nonzero) digits is 6000, while the sum is 28.

The square root of 556520221 is about 23590.6808083192. The cubic root of 556520221 is about 822.5462302215.

Adding to 556520221 its reverse (122025655), we get a palindrome (678545876).

The spelling of 556520221 in words is "five hundred fifty-six million, five hundred twenty thousand, two hundred twenty-one".