261311254523565 has 16 divisors (see below), whose sum is σ = 418098354350400. Its totient is φ = 139365886708352.

The previous prime is 261311254523531. The next prime is 261311254523587. The reversal of 261311254523565 is 565325452113162.

It is a cyclic number.

It is not a de Polignac number, because 261311254523565 - 2²⁶ = 261311187414701 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13322866 + ... + 26459804.

It is an arithmetic number, because the mean of its divisors is an integer number (26131147146900).

Almost surely, 2^{261311254523565} is an apocalyptic number.

It is an amenable number.

261311254523565 is a deficient number, since it is larger than the sum of its proper divisors (156787099826835).

261311254523565 is a wasteful number, since it uses less digits than its factorization.

261311254523565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14463036.

The product of its digits is 6480000, while the sum is 51.

The spelling of 261311254523565 in words is "two hundred sixty-one trillion, three hundred eleven billion, two hundred fifty-four million, five hundred twenty-three thousand, five hundred sixty-five".