81687789594 has 12 divisors (see below), whose sum is σ = 176990210826. Its totient is φ = 27229263192.

The previous prime is 81687789577. The next prime is 81687789629. The reversal of 81687789594 is 49598778618.

It can be written as a sum of positive squares in only one way, i.e., 71402787369 + 10285002225 = 267213^2 + 101415^2 .

It is a super-2 number, since 2×81687789594² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2269105249 + ... + 2269105284.

Almost surely, 2^81687789594 is an apocalyptic number.

81687789594 is an abundant number, since it is smaller than the sum of its proper divisors (95302421232).

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

81687789594 is a wasteful number, since it uses less digits than its factorization.

81687789594 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4538210541 (or 4538210538 counting only the distinct ones).

The product of its digits is 243855360, while the sum is 72.

The spelling of 81687789594 in words is "eighty-one billion, six hundred eighty-seven million, seven hundred eighty-nine thousand, five hundred ninety-four".