261771343681 has 4 divisors (see below), whose sum is σ = 267859049392. Its totient is φ = 255683637972.

The previous prime is 261771343657. The next prime is 261771343693. The reversal of 261771343681 is 186343177162.

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 261771343681 - 2¹³ = 261771335489 is a prime.

It is a super-2 number, since 2×261771343681² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261771343601) 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, 3043852791 + ... + 3043852876.

It is an arithmetic number, because the mean of its divisors is an integer number (66964762348).

Almost surely, 2^261771343681 is an apocalyptic number.

It is an amenable number.

261771343681 is a deficient number, since it is larger than the sum of its proper divisors (6087705711).

261771343681 is an equidigital number, since it uses as much as digits as its factorization.

261771343681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6087705710.

The product of its digits is 1016064, while the sum is 49.

The spelling of 261771343681 in words is "two hundred sixty-one billion, seven hundred seventy-one million, three hundred forty-three thousand, six hundred eighty-one".