81914975999 has 4 divisors (see below), whose sum is σ = 83257844520. Its totient is φ = 80572107480.

The previous prime is 81914975921. The next prime is 81914976001. The reversal of 81914975999 is 99957941918.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81914975999 - 2²⁴ = 81898198783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81914975699) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 671434169 + ... + 671434290.

It is an arithmetic number, because the mean of its divisors is an integer number (20814461130).

Almost surely, 2^81914975999 is an apocalyptic number.

81914975999 is a deficient number, since it is larger than the sum of its proper divisors (1342868521).

81914975999 is a wasteful number, since it uses less digits than its factorization.

81914975999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1342868520.

The product of its digits is 66134880, while the sum is 71.

The spelling of 81914975999 in words is "eighty-one billion, nine hundred fourteen million, nine hundred seventy-five thousand, nine hundred ninety-nine".