81136500 has 48 divisors (see below), whose sum is σ = 236273856. Its totient is φ = 21636000.

The previous prime is 81136493. The next prime is 81136511. The reversal of 81136500 is 563118.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25546 + ... + 28545.

It is an arithmetic number, because the mean of its divisors is an integer number (4922372).

Almost surely, 2^81136500 is an apocalyptic number.

It is an amenable number.

81136500 is an abundant number, since it is smaller than the sum of its proper divisors (155137356).

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

81136500 is a wasteful number, since it uses less digits than its factorization.

81136500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54113 (or 54101 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 81136500 is about 9007.5801411922. The cubic root of 81136500 is about 432.9177804551.

Adding to 81136500 its reverse (563118), we get a palindrome (81699618).

The spelling of 81136500 in words is "eighty-one million, one hundred thirty-six thousand, five hundred".