161831988 has 36 divisors (see below), whose sum is σ = 409771908. Its totient is φ = 53852160.

The previous prime is 161831983. The next prime is 161832007. The reversal of 161831988 is 889138161.

161831988 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 141419664 + 20412324 = 11892^2 + 4518^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161831983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19570 + ... + 26582.

It is an arithmetic number, because the mean of its divisors is an integer number (11382553).

Almost surely, 2^161831988 is an apocalyptic number.

161831988 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

161831988 is an abundant number, since it is smaller than the sum of its proper divisors (247939920).

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

161831988 is a wasteful number, since it uses less digits than its factorization.

161831988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7664 (or 7659 counting only the distinct ones).

The product of its digits is 82944, while the sum is 45.

The square root of 161831988 is about 12721.3202145060. The cubic root of 161831988 is about 544.9476570666.

The spelling of 161831988 in words is "one hundred sixty-one million, eight hundred thirty-one thousand, nine hundred eighty-eight".