556728021 has 12 divisors (see below), whose sum is σ = 804368448. Its totient is φ = 371057064.

The previous prime is 556728017. The next prime is 556728023. The reversal of 556728021 is 120827655.

It is a happy number.

556728021 is a `hidden beast` number, since 556 + 7 + 2 + 80 + 21 = 666.

It is not a de Polignac number, because 556728021 - 2² = 556728017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (556728023) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 58996 + ... + 67778.

It is an arithmetic number, because the mean of its divisors is an integer number (67030704).

Almost surely, 2^556728021 is an apocalyptic number.

It is an amenable number.

556728021 is a deficient number, since it is larger than the sum of its proper divisors (247640427).

556728021 is a wasteful number, since it uses less digits than its factorization.

556728021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15832 (or 15829 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 36.

The square root of 556728021 is about 23595.0846788055. The cubic root of 556728021 is about 822.6485947781.

The spelling of 556728021 in words is "five hundred fifty-six million, seven hundred twenty-eight thousand, twenty-one".