81965895169 has 4 divisors (see below), whose sum is σ = 82046810196. Its totient is φ = 81884980144.

The previous prime is 81965895157. The next prime is 81965895203. The reversal of 81965895169 is 96159856918.

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

It can be written as a sum of positive squares in 2 ways, for example, as 33594490944 + 48371404225 = 183288^2 + 219935^2 .

It is a cyclic number.

It is not a de Polignac number, because 81965895169 - 2⁹ = 81965894657 is a prime.

It is a super-3 number, since 3×81965895169³ (a number of 34 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81965895149) 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, 40455994 + ... + 40458019.

It is an arithmetic number, because the mean of its divisors is an integer number (20511702549).

Almost surely, 2^81965895169 is an apocalyptic number.

It is an amenable number.

81965895169 is a deficient number, since it is larger than the sum of its proper divisors (80915027).

81965895169 is a wasteful number, since it uses less digits than its factorization.

81965895169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80915026.

The product of its digits is 41990400, while the sum is 67.

The spelling of 81965895169 in words is "eighty-one billion, nine hundred sixty-five million, eight hundred ninety-five thousand, one hundred sixty-nine".