2566565861 has 4 divisors (see below), whose sum is σ = 2568840300. Its totient is φ = 2564291424.

The previous prime is 2566565831. The next prime is 2566565873. The reversal of 2566565861 is 1685656652.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 449185636 + 2117380225 = 21194^2 + 46015^2 .

It is a cyclic number.

It is not a de Polignac number, because 2566565861 - 2⁶ = 2566565797 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 (2566565831) 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, 1135526 + ... + 1137783.

It is an arithmetic number, because the mean of its divisors is an integer number (642210075).

Almost surely, 2^2566565861 is an apocalyptic number.

It is an amenable number.

2566565861 is a deficient number, since it is larger than the sum of its proper divisors (2274439).

2566565861 is a wasteful number, since it uses less digits than its factorization.

2566565861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2274438.

The product of its digits is 2592000, while the sum is 50.

The square root of 2566565861 is about 50661.2856232449. The cubic root of 2566565861 is about 1369.1492864392.

The spelling of 2566565861 in words is "two billion, five hundred sixty-six million, five hundred sixty-five thousand, eight hundred sixty-one".