81684689830769 has 4 divisors (see below), whose sum is σ = 81684862477044. Its totient is φ = 81684517184496.

The previous prime is 81684689830759. The next prime is 81684689830781. The reversal of 81684689830769 is 96703898648618.

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 17364097350625 + 64320592480144 = 4167025^2 + 8020012^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81684689830769 is a prime.

It is a super-2 number, since 2×81684689830769² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81684689830739) 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, 85611482 + ... + 86560355.

It is an arithmetic number, because the mean of its divisors is an integer number (20421215619261).

Almost surely, 2^{81684689830769} is an apocalyptic number.

It is an amenable number.

81684689830769 is a deficient number, since it is larger than the sum of its proper divisors (172646275).

81684689830769 is a wasteful number, since it uses less digits than its factorization.

81684689830769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172646274.

The product of its (nonzero) digits is 6019743744, while the sum is 83.

The spelling of 81684689830769 in words is "eighty-one trillion, six hundred eighty-four billion, six hundred eighty-nine million, eight hundred thirty thousand, seven hundred sixty-nine".