81865080 has 160 divisors (see below), whose sum is σ = 300302640. Its totient is φ = 19837440.

The previous prime is 81865067. The next prime is 81865087. The reversal of 81865080 is 8056818.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81865087) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 34492 + ... + 36788.

Almost surely, 2^81865080 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 81865080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150151320).

81865080 is an abundant number, since it is smaller than the sum of its proper divisors (218437560).

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

81865080 is a wasteful number, since it uses less digits than its factorization.

81865080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2331 (or 2318 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 36.

The square root of 81865080 is about 9047.9323604899. The cubic root of 81865080 is about 434.2097423909.

The spelling of 81865080 in words is "eighty-one million, eight hundred sixty-five thousand, eighty".