81823872 has 128 divisors (see below), whose sum is σ = 240932160. Its totient is φ = 24440832.

The previous prime is 81823871. The next prime is 81823913. The reversal of 81823872 is 27832818.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 81823872.

It is not an unprimeable number, because it can be changed into a prime (81823871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 184483 + ... + 184925.

Almost surely, 2^81823872 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 81823872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120466080).

81823872 is an abundant number, since it is smaller than the sum of its proper divisors (159108288).

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

81823872 is a wasteful number, since it uses less digits than its factorization.

81823872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510 (or 498 counting only the distinct ones).

The product of its digits is 43008, while the sum is 39.

The square root of 81823872 is about 9045.6548684990. The cubic root of 81823872 is about 434.1368748625.

The spelling of 81823872 in words is "eighty-one million, eight hundred twenty-three thousand, eight hundred seventy-two".