81569684688 has 20 divisors (see below), whose sum is σ = 210721685568. Its totient is φ = 27189894880.

The previous prime is 81569684683. The next prime is 81569684717. The reversal of 81569684688 is 88648696518.

It is a happy number.

It is a super-2 number, since 2×81569684688² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81569684683) 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, 849684168 + ... + 849684263.

Almost surely, 2^81569684688 is an apocalyptic number.

It is an amenable number.

81569684688 is an abundant number, since it is smaller than the sum of its proper divisors (129152000880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81569684688 is a wasteful number, since it uses less digits than its factorization.

81569684688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1699368442 (or 1699368436 counting only the distinct ones).

The product of its digits is 159252480, while the sum is 69.

The spelling of 81569684688 in words is "eighty-one billion, five hundred sixty-nine million, six hundred eighty-four thousand, six hundred eighty-eight".