265939561 has 4 divisors (see below), whose sum is σ = 279936400. Its totient is φ = 251942724.

The previous prime is 265939543. The next prime is 265939573. The reversal of 265939561 is 165939562.

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, and also an emirpimes, since its reverse is a distinct semiprime: 165939562 = 2 ⋅82969781.

It is a cyclic number.

It is not a de Polignac number, because 265939561 - 2¹⁷ = 265808489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (265939061) 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, 6998391 + ... + 6998428.

It is an arithmetic number, because the mean of its divisors is an integer number (69984100).

Almost surely, 2^265939561 is an apocalyptic number.

It is an amenable number.

265939561 is a deficient number, since it is larger than the sum of its proper divisors (13996839).

265939561 is a wasteful number, since it uses less digits than its factorization.

265939561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13996838.

The product of its digits is 437400, while the sum is 46.

The square root of 265939561 is about 16307.6534486112. The cubic root of 265939561 is about 643.0740465556.

Subtracting from 265939561 its reverse (165939562), we obtain a palindrome (99999999).

The spelling of 265939561 in words is "two hundred sixty-five million, nine hundred thirty-nine thousand, five hundred sixty-one".