81115992 has 80 divisors (see below), whose sum is σ = 228980400. Its totient is φ = 26827200.

The previous prime is 81115967. The next prime is 81116041. The reversal of 81115992 is 29951118.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 97434 + ... + 98262.

It is an arithmetic number, because the mean of its divisors is an integer number (2862255).

Almost surely, 2^81115992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81115992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114490200).

81115992 is an abundant number, since it is smaller than the sum of its proper divisors (147864408).

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

81115992 is a wasteful number, since it uses less digits than its factorization.

81115992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 998 (or 985 counting only the distinct ones).

The product of its digits is 6480, while the sum is 36.

The square root of 81115992 is about 9006.4416946983. The cubic root of 81115992 is about 432.8813027253.

The spelling of 81115992 in words is "eighty-one million, one hundred fifteen thousand, nine hundred ninety-two".