81923965897 has 4 divisors (see below), whose sum is σ = 82036654336. Its totient is φ = 81811277460.

The previous prime is 81923965891. The next prime is 81923965909. The reversal of 81923965897 is 79856932918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81923965897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81923965891) 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, 56343129 + ... + 56344582.

It is an arithmetic number, because the mean of its divisors is an integer number (20509163584).

Almost surely, 2^81923965897 is an apocalyptic number.

It is an amenable number.

81923965897 is a deficient number, since it is larger than the sum of its proper divisors (112688439).

81923965897 is a wasteful number, since it uses less digits than its factorization.

81923965897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112688438.

The product of its digits is 58786560, while the sum is 67.

The spelling of 81923965897 in words is "eighty-one billion, nine hundred twenty-three million, nine hundred sixty-five thousand, eight hundred ninety-seven".