81508578500 has 24 divisors (see below), whose sum is σ = 178014736536. Its totient is φ = 32603431200.

The previous prime is 81508578499. The next prime is 81508578509. The reversal of 81508578500 is 587580518.

It can be written as a sum of positive squares in 4 ways, for example, as 10492724356 + 71015854144 = 102434^2 + 266488^2 .

It is a super-3 number, since 3×81508578500³ (a number of 34 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81508578509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81508079 + ... + 81509078.

It is an arithmetic number, because the mean of its divisors is an integer number (7417280689).

Almost surely, 2^81508578500 is an apocalyptic number.

It is an amenable number.

81508578500 is an abundant number, since it is smaller than the sum of its proper divisors (96506158036).

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

81508578500 is a wasteful number, since it uses less digits than its factorization.

81508578500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163017176 (or 163017164 counting only the distinct ones).

The product of its (nonzero) digits is 448000, while the sum is 47.

The spelling of 81508578500 in words is "eighty-one billion, five hundred eight million, five hundred seventy-eight thousand, five hundred".