81138087 has 6 divisors (see below), whose sum is σ = 117199472. Its totient is φ = 54092052.

The previous prime is 81138073. The next prime is 81138091. The reversal of 81138087 is 78083118.

It is not a de Polignac number, because 81138087 - 2⁶ = 81138023 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81138287) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 4507663 + ... + 4507680.

Almost surely, 2^81138087 is an apocalyptic number.

81138087 is a deficient number, since it is larger than the sum of its proper divisors (36061385).

81138087 is a wasteful number, since it uses less digits than its factorization.

81138087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9015349 (or 9015346 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 81138087 is about 9007.6682332333. The cubic root of 81138087 is about 432.9206030074.

The spelling of 81138087 in words is "eighty-one million, one hundred thirty-eight thousand, eighty-seven".