81136013771 has 4 divisors (see below), whose sum is σ = 82163052000. Its totient is φ = 80108975544.

The previous prime is 81136013759. The next prime is 81136013797. The reversal of 81136013771 is 17731063118.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81136013771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81136013741) 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 3 ways as a sum of consecutive naturals, for example, 513518996 + ... + 513519153.

It is an arithmetic number, because the mean of its divisors is an integer number (20540763000).

Almost surely, 2^81136013771 is an apocalyptic number.

81136013771 is a deficient number, since it is larger than the sum of its proper divisors (1027038229).

81136013771 is a wasteful number, since it uses less digits than its factorization.

81136013771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1027038228.

The product of its (nonzero) digits is 21168, while the sum is 38.

Adding to 81136013771 its reverse (17731063118), we get a palindrome (98867076889).

The spelling of 81136013771 in words is "eighty-one billion, one hundred thirty-six million, thirteen thousand, seven hundred seventy-one".