81038565861 has 16 divisors (see below), whose sum is σ = 122999247360. Its totient is φ = 46978878320.

The previous prime is 81038565857. The next prime is 81038565911. The reversal of 81038565861 is 16856583018.

It is not a de Polignac number, because 81038565861 - 2² = 81038565857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81038565851) by changing a digit.

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 in 15 ways as a sum of consecutive naturals, for example, 53384331 + ... + 53385848.

It is an arithmetic number, because the mean of its divisors is an integer number (7687452960).

Almost surely, 2^81038565861 is an apocalyptic number.

It is an amenable number.

81038565861 is a deficient number, since it is larger than the sum of its proper divisors (41960681499).

81038565861 is a wasteful number, since it uses less digits than its factorization.

81038565861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106770216.

The product of its (nonzero) digits is 1382400, while the sum is 51.

The spelling of 81038565861 in words is "eighty-one billion, thirty-eight million, five hundred sixty-five thousand, eight hundred sixty-one".