11661561656564 has 12 divisors (see below), whose sum is σ = 21608187775524. Its totient is φ = 5487793720704.

The previous prime is 11661561656539. The next prime is 11661561656579. The reversal of 11661561656564 is 46565616516611.

It can be written as a sum of positive squares in 2 ways, for example, as 4081781796964 + 7579779859600 = 2020342^2 + 2753140^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85746776819 + ... + 85746776954.

It is an arithmetic number, because the mean of its divisors is an integer number (1800682314627).

Almost surely, 2^{11661561656564} is an apocalyptic number.

It is an amenable number.

11661561656564 is a deficient number, since it is larger than the sum of its proper divisors (9946626118960).

11661561656564 is a wasteful number, since it uses less digits than its factorization.

11661561656564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171493553794 (or 171493553792 counting only the distinct ones).

The product of its digits is 23328000, while the sum is 59.

The spelling of 11661561656564 in words is "eleven trillion, six hundred sixty-one billion, five hundred sixty-one million, six hundred fifty-six thousand, five hundred sixty-four".