261271161 has 12 divisors (see below), whose sum is σ = 382562388. Its totient is φ = 171794304.

The previous prime is 261271151. The next prime is 261271163. The reversal of 261271161 is 161172162.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 179024400 + 82246761 = 13380^2 + 9069^2 .

It is not a de Polignac number, because 261271161 - 2²² = 257076857 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261271163) 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 11 ways as a sum of consecutive naturals, for example, 198180 + ... + 199493.

It is an arithmetic number, because the mean of its divisors is an integer number (31880199).

Almost surely, 2^261271161 is an apocalyptic number.

It is an amenable number.

261271161 is a deficient number, since it is larger than the sum of its proper divisors (121291227).

261271161 is a wasteful number, since it uses less digits than its factorization.

261271161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397752 (or 397749 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 261271161 is about 16163.8844650659. The cubic root of 261271161 is about 639.2888919794.

The spelling of 261271161 in words is "two hundred sixty-one million, two hundred seventy-one thousand, one hundred sixty-one".