81100523138 has 4 divisors (see below), whose sum is σ = 121650784710. Its totient is φ = 40550261568.

The previous prime is 81100523081. The next prime is 81100523149. The reversal of 81100523138 is 83132500118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 70701214609 + 10399308529 = 265897^2 + 101977^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20275130783 + ... + 20275130786.

Almost surely, 2^81100523138 is an apocalyptic number.

81100523138 is a deficient number, since it is larger than the sum of its proper divisors (40550261572).

81100523138 is a wasteful number, since it uses less digits than its factorization.

81100523138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40550261571.

The product of its (nonzero) digits is 5760, while the sum is 32.

The spelling of 81100523138 in words is "eighty-one billion, one hundred million, five hundred twenty-three thousand, one hundred thirty-eight".