556388621 has 2 divisors, whose sum is σ = 556388622. Its totient is φ = 556388620.

The previous prime is 556388557. The next prime is 556388639. The reversal of 556388621 is 126883655.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 316448521 + 239940100 = 17789^2 + 15490^2 .

It is a cyclic number.

It is not a de Polignac number, because 556388621 - 2⁶ = 556388557 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (556388671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 278194310 + 278194311.

It is an arithmetic number, because the mean of its divisors is an integer number (278194311).

Almost surely, 2^556388621 is an apocalyptic number.

It is an amenable number.

556388621 is a deficient number, since it is larger than the sum of its proper divisors (1).

556388621 is an equidigital number, since it uses as much as digits as its factorization.

556388621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 44.

The square root of 556388621 is about 23587.8914063975. The cubic root of 556388621 is about 822.4813894404.

The spelling of 556388621 in words is "five hundred fifty-six million, three hundred eighty-eight thousand, six hundred twenty-one".