265565561 has 4 divisors (see below), whose sum is σ = 274132224. Its totient is φ = 256998900.

The previous prime is 265565543. The next prime is 265565579. The reversal of 265565561 is 165565562.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (265565543) and next prime (265565579).

It is a cyclic number.

It is not a de Polignac number, because 265565561 - 2⁶ = 265565497 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (265565501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4283285 + ... + 4283346.

It is an arithmetic number, because the mean of its divisors is an integer number (68533056).

Almost surely, 2^265565561 is an apocalyptic number.

It is an amenable number.

265565561 is a deficient number, since it is larger than the sum of its proper divisors (8566663).

265565561 is an equidigital number, since it uses as much as digits as its factorization.

265565561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8566662.

The product of its digits is 270000, while the sum is 41.

The square root of 265565561 is about 16296.1824057047. The cubic root of 265565561 is about 642.7724460386.

Subtracting from 265565561 its reverse (165565562), we obtain a palindrome (99999999).

The spelling of 265565561 in words is "two hundred sixty-five million, five hundred sixty-five thousand, five hundred sixty-one".