81808173994 has 16 divisors (see below), whose sum is σ = 123480979200. Its totient is φ = 40647912480.

The previous prime is 81808173991. The next prime is 81808174069. The reversal of 81808173994 is 49937180818.

It is not an unprimeable number, because it can be changed into a prime (81808173991) 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 7 ways as a sum of consecutive naturals, for example, 4244359 + ... + 4263589.

It is an arithmetic number, because the mean of its divisors is an integer number (7717561200).

Almost surely, 2^81808173994 is an apocalyptic number.

81808173994 is a deficient number, since it is larger than the sum of its proper divisors (41672805206).

81808173994 is a wasteful number, since it uses less digits than its factorization.

81808173994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32445.

The product of its (nonzero) digits is 3483648, while the sum is 58.

The spelling of 81808173994 in words is "eighty-one billion, eight hundred eight million, one hundred seventy-three thousand, nine hundred ninety-four".