81939132 has 36 divisors (see below), whose sum is σ = 225954456. Its totient is φ = 24829920.

The previous prime is 81939131. The next prime is 81939139. The reversal of 81939132 is 23193918.

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

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81939131) 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, 103063 + ... + 103854.

Almost surely, 2^81939132 is an apocalyptic number.

It is an amenable number.

81939132 is an abundant number, since it is smaller than the sum of its proper divisors (144015324).

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

81939132 is a wasteful number, since it uses less digits than its factorization.

81939132 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206938 (or 206933 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 81939132 is about 9052.0236411534. The cubic root of 81939132 is about 434.3406260741.

The spelling of 81939132 in words is "eighty-one million, nine hundred thirty-nine thousand, one hundred thirty-two".