81599824139 has 2 divisors, whose sum is σ = 81599824140. Its totient is φ = 81599824138.

The previous prime is 81599824129. The next prime is 81599824177. The reversal of 81599824139 is 93142899518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81599824139 - 2⁴ = 81599824123 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (81599824129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40799912069 + 40799912070.

It is an arithmetic number, because the mean of its divisors is an integer number (40799912070).

Almost surely, 2^81599824139 is an apocalyptic number.

81599824139 is a deficient number, since it is larger than the sum of its proper divisors (1).

81599824139 is an equidigital number, since it uses as much as digits as its factorization.

81599824139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5598720, while the sum is 59.

The spelling of 81599824139 in words is "eighty-one billion, five hundred ninety-nine million, eight hundred twenty-four thousand, one hundred thirty-nine".