161811928161 has 12 divisors (see below), whose sum is σ = 251707443988. Its totient is φ = 99576571104.

The previous prime is 161811928153. The next prime is 161811928183. The reversal of 161811928161 is 161829118161.

It is a happy number.

161811928161 is a `hidden beast` number, since 1 + 618 + 1 + 1 + 9 + 28 + 1 + 6 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 71532711936 + 90279216225 = 267456^2 + 300465^2 .

It is not a de Polignac number, because 161811928161 - 2³ = 161811928153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161811928151) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 691503850 + ... + 691504083.

Almost surely, 2^161811928161 is an apocalyptic number.

It is an amenable number.

161811928161 is a deficient number, since it is larger than the sum of its proper divisors (89895515827).

161811928161 is a wasteful number, since it uses less digits than its factorization.

161811928161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1383007952 (or 1383007949 counting only the distinct ones).

The product of its digits is 41472, while the sum is 45.

The spelling of 161811928161 in words is "one hundred sixty-one billion, eight hundred eleven million, nine hundred twenty-eight thousand, one hundred sixty-one".