2005656561 has 12 divisors (see below), whose sum is σ = 2946162960. Its totient is φ = 1314441240.

The previous prime is 2005656553. The next prime is 2005656607. The reversal of 2005656561 is 1656565002.

It is a happy number.

It is not a de Polignac number, because 2005656561 - 2³ = 2005656553 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2005656551) 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, 1888035 + ... + 1889096.

It is an arithmetic number, because the mean of its divisors is an integer number (245513580).

Almost surely, 2^2005656561 is an apocalyptic number.

It is an amenable number.

2005656561 is a deficient number, since it is larger than the sum of its proper divisors (940506399).

2005656561 is a wasteful number, since it uses less digits than its factorization.

2005656561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3777196 (or 3777193 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The square root of 2005656561 is about 44784.5571709713. The cubic root of 2005656561 is about 1261.1077352164.

The spelling of 2005656561 in words is "two billion, five million, six hundred fifty-six thousand, five hundred sixty-one".