81588889556 has 12 divisors (see below), whose sum is σ = 146263009620. Its totient is φ = 39799458240.

The previous prime is 81588889549. The next prime is 81588889649. The reversal of 81588889556 is 65598888518.

It can be written as a sum of positive squares in 2 ways, for example, as 28996640656 + 52592248900 = 170284^2 + 229330^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81588889556.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 248746451 + ... + 248746778.

It is an arithmetic number, because the mean of its divisors is an integer number (12188584135).

Almost surely, 2^81588889556 is an apocalyptic number.

It is an amenable number.

81588889556 is a deficient number, since it is larger than the sum of its proper divisors (64674120064).

81588889556 is a wasteful number, since it uses less digits than its factorization.

81588889556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497493274 (or 497493272 counting only the distinct ones).

The product of its digits is 221184000, while the sum is 71.

The spelling of 81588889556 in words is "eighty-one billion, five hundred eighty-eight million, eight hundred eighty-nine thousand, five hundred fifty-six".