81537699599 has 2 divisors, whose sum is σ = 81537699600. Its totient is φ = 81537699598.

The previous prime is 81537699559. The next prime is 81537699601. The reversal of 81537699599 is 99599673518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81537699599 - 2³⁶ = 12818222863 is a prime.

It is a Sophie Germain prime.

Together with 81537699601, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81537699559) 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 as a sum of consecutive naturals, namely, 40768849799 + 40768849800.

It is an arithmetic number, because the mean of its divisors is an integer number (40768849800).

Almost surely, 2^81537699599 is an apocalyptic number.

81537699599 is a deficient number, since it is larger than the sum of its proper divisors (1).

81537699599 is an equidigital number, since it uses as much as digits as its factorization.

81537699599 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165337200, while the sum is 71.

The spelling of 81537699599 in words is "eighty-one billion, five hundred thirty-seven million, six hundred ninety-nine thousand, five hundred ninety-nine".