81699439982 has 4 divisors (see below), whose sum is σ = 122549159976. Its totient is φ = 40849719990.

The previous prime is 81699439933. The next prime is 81699439993. The reversal of 81699439982 is 28993499618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 28993499618 = 2 ⋅14496749809.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 20424859994 + ... + 20424859997.

It is an arithmetic number, because the mean of its divisors is an integer number (30637289994).

Almost surely, 2^81699439982 is an apocalyptic number.

81699439982 is a deficient number, since it is larger than the sum of its proper divisors (40849719994).

81699439982 is a wasteful number, since it uses less digits than its factorization.

81699439982 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40849719993.

The product of its digits is 60466176, while the sum is 68.

The spelling of 81699439982 in words is "eighty-one billion, six hundred ninety-nine million, four hundred thirty-nine thousand, nine hundred eighty-two".