261141561 has 6 divisors (see below), whose sum is σ = 377204490. Its totient is φ = 174094368.

The previous prime is 261141527. The next prime is 261141571. The reversal of 261141561 is 165141162.

261141561 is a `hidden beast` number, since 2 + 61 + 1 + 41 + 561 = 666.

261141561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 134444025 + 126697536 = 11595^2 + 11256^2 .

It is not a de Polignac number, because 261141561 - 2⁶ = 261141497 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261141511) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14507856 + ... + 14507873.

It is an arithmetic number, because the mean of its divisors is an integer number (62867415).

Almost surely, 2^261141561 is an apocalyptic number.

It is an amenable number.

261141561 is a deficient number, since it is larger than the sum of its proper divisors (116062929).

261141561 is a wasteful number, since it uses less digits than its factorization.

261141561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29015735 (or 29015732 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 261141561 is about 16159.8750304574. The cubic root of 261141561 is about 639.1831709818.

The spelling of 261141561 in words is "two hundred sixty-one million, one hundred forty-one thousand, five hundred sixty-one".