81985812 has 12 divisors (see below), whose sum is σ = 191300256. Its totient is φ = 27328600.

The previous prime is 81985807. The next prime is 81985819. The reversal of 81985812 is 21858918.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81985819) 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, 3416064 + ... + 3416087.

It is an arithmetic number, because the mean of its divisors is an integer number (15941688).

Almost surely, 2^81985812 is an apocalyptic number.

It is an amenable number.

81985812 is an abundant number, since it is smaller than the sum of its proper divisors (109314444).

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

81985812 is a wasteful number, since it uses less digits than its factorization.

81985812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6832158 (or 6832156 counting only the distinct ones).

The product of its digits is 46080, while the sum is 42.

The square root of 81985812 is about 9054.6017030016. The cubic root of 81985812 is about 434.4230904229.

The spelling of 81985812 in words is "eighty-one million, nine hundred eighty-five thousand, eight hundred twelve".