81599994 has 48 divisors (see below), whose sum is σ = 210945600. Its totient is φ = 23313528.

The previous prime is 81599993. The next prime is 81600023. The reversal of 81599994 is 49999518.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81599994.

It is not an unprimeable number, because it can be changed into a prime (81599993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12774 + ... + 18065.

It is an arithmetic number, because the mean of its divisors is an integer number (4394700).

Almost surely, 2^81599994 is an apocalyptic number.

81599994 is an abundant number, since it is smaller than the sum of its proper divisors (129345606).

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

81599994 is a wasteful number, since it uses less digits than its factorization.

81599994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30864 (or 30851 counting only the distinct ones).

The product of its digits is 1049760, while the sum is 54.

The square root of 81599994 is about 9033.2715004034. The cubic root of 81599994 is about 433.7405664191.

The spelling of 81599994 in words is "eighty-one million, five hundred ninety-nine thousand, nine hundred ninety-four".