1556655561 has 6 divisors (see below), whose sum is σ = 2248502490. Its totient is φ = 1037770368.

The previous prime is 1556655559. The next prime is 1556655563. The reversal of 1556655561 is 1655566551.

1556655561 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (1556655559) and next prime (1556655563).

It can be written as a sum of positive squares in only one way, i.e., 1138657536 + 417998025 = 33744^2 + 20445^2 .

It is not a de Polignac number, because 1556655561 - 2¹ = 1556655559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1556655563) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 86480856 + ... + 86480873.

It is an arithmetic number, because the mean of its divisors is an integer number (374750415).

Almost surely, 2^1556655561 is an apocalyptic number.

It is an amenable number.

1556655561 is a deficient number, since it is larger than the sum of its proper divisors (691846929).

1556655561 is a wasteful number, since it uses less digits than its factorization.

1556655561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172961735 (or 172961732 counting only the distinct ones).

The product of its digits is 675000, while the sum is 45.

The square root of 1556655561 is about 39454.4745371168. The cubic root of 1556655561 is about 1158.9486016737.

The spelling of 1556655561 in words is "one billion, five hundred fifty-six million, six hundred fifty-five thousand, five hundred sixty-one".