81891792 has 60 divisors (see below), whose sum is σ = 229793824. Its totient is φ = 27224640.

The previous prime is 81891787. The next prime is 81891827. The reversal of 81891792 is 29719818.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 99093 + ... + 99915.

Almost surely, 2^81891792 is an apocalyptic number.

It is an amenable number.

81891792 is an abundant number, since it is smaller than the sum of its proper divisors (147902032).

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

81891792 is a wasteful number, since it uses less digits than its factorization.

81891792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1528 (or 1519 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 81891792 is about 9049.4083784522. The cubic root of 81891792 is about 434.2569637840.

The spelling of 81891792 in words is "eighty-one million, eight hundred ninety-one thousand, seven hundred ninety-two".