81440768 has 52 divisors (see below), whose sum is σ = 166113480. Its totient is φ = 39911424.

The previous prime is 81440759. The next prime is 81440797. The reversal of 81440768 is 86704418.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 241496 + ... + 241832.

It is an arithmetic number, because the mean of its divisors is an integer number (3194490).

Almost surely, 2^81440768 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 81440768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83056740).

81440768 is an abundant number, since it is smaller than the sum of its proper divisors (84672712).

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

81440768 is an equidigital number, since it uses as much as digits as its factorization.

81440768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 420 (or 398 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 38.

The square root of 81440768 is about 9024.4538892944. The cubic root of 81440768 is about 433.4582635189.

The spelling of 81440768 in words is "eighty-one million, four hundred forty thousand, seven hundred sixty-eight".