2565436561 has 4 divisors (see below), whose sum is σ = 2716344612. Its totient is φ = 2414528512.

The previous prime is 2565436519. The next prime is 2565436603. The reversal of 2565436561 is 1656345652.

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

It is an interprime number because it is at equal distance from previous prime (2565436519) and next prime (2565436603).

It can be written as a sum of positive squares in 2 ways, for example, as 1207145536 + 1358291025 = 34744^2 + 36855^2 .

It is a cyclic number.

It is not a de Polignac number, because 2565436561 - 2¹⁵ = 2565403793 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2565436501) 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, 75454000 + ... + 75454033.

It is an arithmetic number, because the mean of its divisors is an integer number (679086153).

Almost surely, 2^2565436561 is an apocalyptic number.

It is an amenable number.

2565436561 is a deficient number, since it is larger than the sum of its proper divisors (150908051).

2565436561 is a wasteful number, since it uses less digits than its factorization.

2565436561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150908050.

The product of its digits is 648000, while the sum is 43.

The square root of 2565436561 is about 50650.1388053379. The cubic root of 2565436561 is about 1368.9484464577.

Subtracting from 2565436561 its reverse (1656345652), we obtain a palindrome (909090909).

The spelling of 2565436561 in words is "two billion, five hundred sixty-five million, four hundred thirty-six thousand, five hundred sixty-one".