81691910089 has 8 divisors (see below), whose sum is σ = 82369918400. Its totient is φ = 81016577136.

The previous prime is 81691910063. The next prime is 81691910119. The reversal of 81691910089 is 98001919618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81691910089 - 2⁷ = 81691909961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81691310089) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 607494 + ... + 729679.

It is an arithmetic number, because the mean of its divisors is an integer number (10296239800).

Almost surely, 2^81691910089 is an apocalyptic number.

It is an amenable number.

81691910089 is a deficient number, since it is larger than the sum of its proper divisors (678008311).

81691910089 is a wasteful number, since it uses less digits than its factorization.

81691910089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1337679.

The product of its (nonzero) digits is 279936, while the sum is 52.

The spelling of 81691910089 in words is "eighty-one billion, six hundred ninety-one million, nine hundred ten thousand, eighty-nine".