81445824 has 84 divisors (see below), whose sum is σ = 242142264. Its totient is φ = 27143424.

The previous prime is 81445817. The next prime is 81445841. The reversal of 81445824 is 42854418.

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 11 ways as a sum of consecutive naturals, for example, 12934 + ... + 18170.

It is an arithmetic number, because the mean of its divisors is an integer number (2882646).

Almost surely, 2^81445824 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 81445824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121071132).

81445824 is an abundant number, since it is smaller than the sum of its proper divisors (160696440).

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

81445824 is an equidigital number, since it uses as much as digits as its factorization.

81445824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5264 (or 5242 counting only the distinct ones).

The product of its digits is 40960, while the sum is 36.

The square root of 81445824 is about 9024.7340127009. The cubic root of 81445824 is about 433.4672333084.

The spelling of 81445824 in words is "eighty-one million, four hundred forty-five thousand, eight hundred twenty-four".