81115940 has 48 divisors (see below), whose sum is σ = 187125120. Its totient is φ = 29399040.

The previous prime is 81115939. The next prime is 81115961. The reversal of 81115940 is 4951118.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4100 + ... + 13380.

It is an arithmetic number, because the mean of its divisors is an integer number (3898440).

Almost surely, 2^81115940 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 81115940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93562560).

81115940 is an abundant number, since it is smaller than the sum of its proper divisors (106009180).

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

81115940 is a wasteful number, since it uses less digits than its factorization.

81115940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9332 (or 9330 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 29.

The square root of 81115940 is about 9006.4388078752. The cubic root of 81115940 is about 432.8812102247.

The spelling of 81115940 in words is "eighty-one million, one hundred fifteen thousand, nine hundred forty".