81530500 has 24 divisors (see below), whose sum is σ = 178063704. Its totient is φ = 32612000.

The previous prime is 81530479. The next prime is 81530503. The reversal of 81530500 is 503518.

It can be written as a sum of positive squares in 4 ways, for example, as 25220484 + 56310016 = 5022^2 + 7504^2 .

It is not an unprimeable number, because it can be changed into a prime (81530503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81031 + ... + 82030.

It is an arithmetic number, because the mean of its divisors is an integer number (7419321).

Almost surely, 2^81530500 is an apocalyptic number.

It is an amenable number.

81530500 is an abundant number, since it is smaller than the sum of its proper divisors (96533204).

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

81530500 is a wasteful number, since it uses less digits than its factorization.

81530500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163080 (or 163068 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 81530500 is about 9029.4241233868. The cubic root of 81530500 is about 433.6174008553.

The spelling of 81530500 in words is "eighty-one million, five hundred thirty thousand, five hundred".