261761161 has 4 divisors (see below), whose sum is σ = 265668112. Its totient is φ = 257854212.

The previous prime is 261761153. The next prime is 261761177. The reversal of 261761161 is 161167162.

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.

It is a cyclic number.

It is not a de Polignac number, because 261761161 - 2³ = 261761153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261761141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1953375 + ... + 1953508.

It is an arithmetic number, because the mean of its divisors is an integer number (66417028).

Almost surely, 2^261761161 is an apocalyptic number.

It is an amenable number.

261761161 is a deficient number, since it is larger than the sum of its proper divisors (3906951).

261761161 is an equidigital number, since it uses as much as digits as its factorization.

261761161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3906950.

The product of its digits is 3024, while the sum is 31.

The square root of 261761161 is about 16179.0346127326. The cubic root of 261761161 is about 639.6882930344.

The spelling of 261761161 in words is "two hundred sixty-one million, seven hundred sixty-one thousand, one hundred sixty-one".