161931816 has 24 divisors (see below), whose sum is σ = 438565530. Its totient is φ = 53977248.

The previous prime is 161931797. The next prime is 161931823. The reversal of 161931816 is 618139161.

It is a happy number.

161931816 is a `hidden beast` number, since 1 + 619 + 31 + 8 + 1 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 159516900 + 2414916 = 12630^2 + 1554^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1124455 + ... + 1124598.

Almost surely, 2^161931816 is an apocalyptic number.

It is an amenable number.

161931816 is an abundant number, since it is smaller than the sum of its proper divisors (276633714).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161931816 is a wasteful number, since it uses less digits than its factorization.

161931816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2249065 (or 2249058 counting only the distinct ones).

The product of its digits is 7776, while the sum is 36.

The square root of 161931816 is about 12725.2432589715. The cubic root of 161931816 is about 545.0596865305.

The spelling of 161931816 in words is "one hundred sixty-one million, nine hundred thirty-one thousand, eight hundred sixteen".