261775964849761 has 4 divisors (see below), whose sum is σ = 277174551017412. Its totient is φ = 246377378682112.

The previous prime is 261775964849687. The next prime is 261775964849797. The reversal of 261775964849761 is 167948469577162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 225442267120225 + 36333697729536 = 15014735^2 + 6027744^2 .

It is a cyclic number.

It is not a de Polignac number, because 261775964849761 - 2³⁷ = 261638525896289 is a prime.

It is a super-2 number, since 2×261775964849761² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261775964843761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7699293083800 + ... + 7699293083833.

It is an arithmetic number, because the mean of its divisors is an integer number (69293637754353).

Almost surely, 2^{261775964849761} is an apocalyptic number.

It is an amenable number.

261775964849761 is a deficient number, since it is larger than the sum of its proper divisors (15398586167651).

261775964849761 is a wasteful number, since it uses less digits than its factorization.

261775964849761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15398586167650.

The product of its digits is 7681443840, while the sum is 82.

The spelling of 261775964849761 in words is "two hundred sixty-one trillion, seven hundred seventy-five billion, nine hundred sixty-four million, eight hundred forty-nine thousand, seven hundred sixty-one".