81385866599 has 6 divisors (see below), whose sum is σ = 81928438200. Its totient is φ = 80846864700.

The previous prime is 81385866593. The next prime is 81385866607. The reversal of 81385866599 is 99566858318.

It is not a de Polignac number, because 81385866599 - 2³⁶ = 12666389863 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 (81385866593) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1761899 + ... + 1807500.

It is an arithmetic number, because the mean of its divisors is an integer number (13654739700).

Almost surely, 2^81385866599 is an apocalyptic number.

81385866599 is a deficient number, since it is larger than the sum of its proper divisors (542571601).

81385866599 is an equidigital number, since it uses as much as digits as its factorization.

81385866599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3569701 (or 3569550 counting only the distinct ones).

The product of its digits is 111974400, while the sum is 68.

The spelling of 81385866599 in words is "eighty-one billion, three hundred eighty-five million, eight hundred sixty-six thousand, five hundred ninety-nine".