81986437865 has 32 divisors (see below), whose sum is σ = 102233456640. Its totient is φ = 63073728000.

The previous prime is 81986437861. The next prime is 81986437877. The reversal of 81986437865 is 56873468918.

It is not a de Polignac number, because 81986437865 - 2² = 81986437861 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81986437861) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16497101 + ... + 16502069.

It is an arithmetic number, because the mean of its divisors is an integer number (3194795520).

Almost surely, 2^81986437865 is an apocalyptic number.

It is an amenable number.

81986437865 is a deficient number, since it is larger than the sum of its proper divisors (20247018775).

81986437865 is a wasteful number, since it uses less digits than its factorization.

81986437865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6233.

The product of its digits is 69672960, while the sum is 65.

The spelling of 81986437865 in words is "eighty-one billion, nine hundred eighty-six million, four hundred thirty-seven thousand, eight hundred sixty-five".