556516021 has 4 divisors (see below), whose sum is σ = 562769100. Its totient is φ = 550262944.

The previous prime is 556516013. The next prime is 556516031. The reversal of 556516021 is 120615655.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120615655 = 5 ⋅24123131.

It can be written as a sum of positive squares in 2 ways, for example, as 254243025 + 302272996 = 15945^2 + 17386^2 .

It is a cyclic number.

It is not a de Polignac number, because 556516021 - 2³ = 556516013 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 (556516031) 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, 3126406 + ... + 3126583.

It is an arithmetic number, because the mean of its divisors is an integer number (140692275).

Almost surely, 2^556516021 is an apocalyptic number.

It is an amenable number.

556516021 is a deficient number, since it is larger than the sum of its proper divisors (6253079).

556516021 is an equidigital number, since it uses as much as digits as its factorization.

556516021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6253078.

The product of its (nonzero) digits is 9000, while the sum is 31.

The square root of 556516021 is about 23590.5917899488. The cubic root of 556516021 is about 822.5441609928.

The spelling of 556516021 in words is "five hundred fifty-six million, five hundred sixteen thousand, twenty-one".