81985892 has 12 divisors (see below), whose sum is σ = 149713536. Its totient is φ = 39210600.

The previous prime is 81985889. The next prime is 81985913. The reversal of 81985892 is 29858918.

It is a self number, because there is not a number n which added to its sum of digits gives 81985892.

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, 445484 + ... + 445667.

It is an arithmetic number, because the mean of its divisors is an integer number (12476128).

Almost surely, 2^81985892 is an apocalyptic number.

It is an amenable number.

81985892 is a deficient number, since it is larger than the sum of its proper divisors (67727644).

81985892 is a wasteful number, since it uses less digits than its factorization.

81985892 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 891178 (or 891176 counting only the distinct ones).

The product of its digits is 414720, while the sum is 50.

The square root of 81985892 is about 9054.6061206438. The cubic root of 81985892 is about 434.4232317231.

The spelling of 81985892 in words is "eighty-one million, nine hundred eighty-five thousand, eight hundred ninety-two".