181991912 has 16 divisors (see below), whose sum is σ = 342075300. Its totient is φ = 90771840.

The previous prime is 181991911. The next prime is 181991941. The reversal of 181991912 is 219199181.

It can be written as a sum of positive squares in 2 ways, for example, as 181872196 + 119716 = 13486^2 + 346^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 181991912.

It is not an unprimeable number, because it can be changed into a prime (181991911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24539 + ... + 31082.

Almost surely, 2^181991912 is an apocalyptic number.

It is an amenable number.

181991912 is a deficient number, since it is larger than the sum of its proper divisors (160083388).

181991912 is a wasteful number, since it uses less digits than its factorization.

181991912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56036 (or 56032 counting only the distinct ones).

The product of its digits is 11664, while the sum is 41.

The square root of 181991912 is about 13490.4377986780. The cubic root of 181991912 is about 566.6967159767.

The spelling of 181991912 in words is "one hundred eighty-one million, nine hundred ninety-one thousand, nine hundred twelve".