81443880 has 384 divisors, whose sum is σ = 336528000. Its totient is φ = 17635968.

The previous prime is 81443867. The next prime is 81443909. The reversal of 81443880 is 8834418.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4286511 + ... + 4286529.

It is an arithmetic number, because the mean of its divisors is an integer number (876375).

Almost surely, 2^81443880 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 81443880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (168264000).

81443880 is an abundant number, since it is smaller than the sum of its proper divisors (255084120).

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

81443880 is a wasteful number, since it uses less digits than its factorization.

81443880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65 (or 36 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The square root of 81443880 is about 9024.6263080529. The cubic root of 81443880 is about 433.4637845250.

The spelling of 81443880 in words is "eighty-one million, four hundred forty-three thousand, eight hundred eighty".