81668384 has 96 divisors (see below), whose sum is σ = 199987200. Its totient is φ = 32037120.

The previous prime is 81668381. The next prime is 81668387. The reversal of 81668384 is 48386618.

It is an interprime number because it is at equal distance from previous prime (81668381) and next prime (81668387).

It is not an unprimeable number, because it can be changed into a prime (81668381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 131627 + ... + 132245.

It is an arithmetic number, because the mean of its divisors is an integer number (2083200).

Almost surely, 2^81668384 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 81668384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99993600).

81668384 is an abundant number, since it is smaller than the sum of its proper divisors (118318816).

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

81668384 is a wasteful number, since it uses less digits than its factorization.

81668384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 686 (or 678 counting only the distinct ones).

The product of its digits is 221184, while the sum is 44.

The square root of 81668384 is about 9037.0561578426. The cubic root of 81668384 is about 433.8617070901.

The spelling of 81668384 in words is "eighty-one million, six hundred sixty-eight thousand, three hundred eighty-four".