261235005165 has 48 divisors (see below), whose sum is σ = 469161162288. Its totient is φ = 134360045568.

The previous prime is 261235005149. The next prime is 261235005167. The reversal of 261235005165 is 561500532162.

261235005165 is a `hidden beast` number, since 2 + 612 + 35 + 0 + 0 + 5 + 1 + 6 + 5 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 4897340361 + 256337664804 = 69981^2 + 506298^2 .

It is not a de Polignac number, because 261235005165 - 2⁴ = 261235005149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261235005167) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 506094 + ... + 882383.

It is an arithmetic number, because the mean of its divisors is an integer number (9774190881).

Almost surely, 2^261235005165 is an apocalyptic number.

It is an amenable number.

261235005165 is a deficient number, since it is larger than the sum of its proper divisors (207926157123).

261235005165 is a wasteful number, since it uses less digits than its factorization.

261235005165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1388638 (or 1388635 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The spelling of 261235005165 in words is "two hundred sixty-one billion, two hundred thirty-five million, five thousand, one hundred sixty-five".