81399168 has 96 divisors (see below), whose sum is σ = 243002760. Its totient is φ = 27122688.

The previous prime is 81399127. The next prime is 81399187. The reversal of 81399168 is 86199318.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a nude number because it is divisible by every one of its digits.

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, 29796 + ... + 32412.

Almost surely, 2^81399168 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 81399168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121501380).

81399168 is an abundant number, since it is smaller than the sum of its proper divisors (161603592).

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

81399168 is an equidigital number, since it uses as much as digits as its factorization.

81399168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2646 (or 2622 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 81399168 is about 9022.1487462799. The cubic root of 81399168 is about 433.3844473565.

The spelling of 81399168 in words is "eighty-one million, three hundred ninety-nine thousand, one hundred sixty-eight".