81939184 has 20 divisors (see below), whose sum is σ = 168096384. Its totient is φ = 38559488.

The previous prime is 81939163. The next prime is 81939199. The reversal of 81939184 is 48193918.

It is a self number, because there is not a number n which added to its sum of digits gives 81939184.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 150352 + ... + 150895.

Almost surely, 2^81939184 is an apocalyptic number.

It is an amenable number.

81939184 is an abundant number, since it is smaller than the sum of its proper divisors (86157200).

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

81939184 is a wasteful number, since it uses less digits than its factorization.

81939184 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301272 (or 301266 counting only the distinct ones).

The product of its digits is 62208, while the sum is 43.

The square root of 81939184 is about 9052.0265134389. The cubic root of 81939184 is about 434.3407179542.

The spelling of 81939184 in words is "eighty-one million, nine hundred thirty-nine thousand, one hundred eighty-four".