2161181938556 has 12 divisors (see below), whose sum is σ = 3782353044120. Its totient is φ = 1080509640240.

The previous prime is 2161181938549. The next prime is 2161181938603. The reversal of 2161181938556 is 6558391811612.

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, 20272451 + ... + 20378778.

It is an arithmetic number, because the mean of its divisors is an integer number (315196087010).

Almost surely, 2^{2161181938556} is an apocalyptic number.

It is an amenable number.

2161181938556 is a deficient number, since it is larger than the sum of its proper divisors (1621171105564).

2161181938556 is a wasteful number, since it uses less digits than its factorization.

2161181938556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40664524 (or 40664522 counting only the distinct ones).

The product of its digits is 3110400, while the sum is 56.

The spelling of 2161181938556 in words is "two trillion, one hundred sixty-one billion, one hundred eighty-one million, nine hundred thirty-eight thousand, five hundred fifty-six".