81569684689 has 4 divisors (see below), whose sum is σ = 81651996160. Its totient is φ = 81487373220.

The previous prime is 81569684683. The next prime is 81569684717. The reversal of 81569684689 is 98648696518.

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, and also an emirpimes, since its reverse is a distinct semiprime: 98648696518 = 2 ⋅49324348259.

It is not a de Polignac number, because 81569684689 - 2⁹ = 81569684177 is a prime.

It is a super-2 number, since 2×81569684689² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81569684683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41154249 + ... + 41156230.

It is an arithmetic number, because the mean of its divisors is an integer number (20412999040).

Almost surely, 2^81569684689 is an apocalyptic number.

It is an amenable number.

81569684689 is a deficient number, since it is larger than the sum of its proper divisors (82311471).

81569684689 is an equidigital number, since it uses as much as digits as its factorization.

81569684689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82311470.

The product of its digits is 179159040, while the sum is 70.

The spelling of 81569684689 in words is "eighty-one billion, five hundred sixty-nine million, six hundred eighty-four thousand, six hundred eighty-nine".