81811923588 has 60 divisors (see below), whose sum is σ = 223171354560. Its totient is φ = 26084958768.

The previous prime is 81811923563. The next prime is 81811923593. The reversal of 81811923588 is 88532911818.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5481808 + ... + 5496711.

It is an arithmetic number, because the mean of its divisors is an integer number (3719522576).

Almost surely, 2^81811923588 is an apocalyptic number.

It is an amenable number.

81811923588 is an abundant number, since it is smaller than the sum of its proper divisors (141359430972).

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

81811923588 is a wasteful number, since it uses less digits than its factorization.

81811923588 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10978558 (or 10978547 counting only the distinct ones).

The product of its digits is 1105920, while the sum is 54.

The spelling of 81811923588 in words is "eighty-one billion, eight hundred eleven million, nine hundred twenty-three thousand, five hundred eighty-eight".