261656581911 has 16 divisors (see below), whose sum is σ = 350160478848. Its totient is φ = 173796386400.

The previous prime is 261656581861. The next prime is 261656581913. The reversal of 261656581911 is 119185656162.

It is a de Polignac number, because none of the positive numbers 2^k-261656581911 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261656581913) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 740416 + ... + 1035146.

It is an arithmetic number, because the mean of its divisors is an integer number (21885029928).

Almost surely, 2^261656581911 is an apocalyptic number.

261656581911 is a deficient number, since it is larger than the sum of its proper divisors (88503896937).

261656581911 is a wasteful number, since it uses less digits than its factorization.

261656581911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295822.

The product of its digits is 777600, while the sum is 51.

The spelling of 261656581911 in words is "two hundred sixty-one billion, six hundred fifty-six million, five hundred eighty-one thousand, nine hundred eleven".