81535534799 has 4 divisors (see below), whose sum is σ = 81991040760. Its totient is φ = 81080028840.

The previous prime is 81535534777. The next prime is 81535534837. The reversal of 81535534799 is 99743553518.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81535534799 - 2²⁴ = 81518757583 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 (81535534099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 227752712 + ... + 227753069.

It is an arithmetic number, because the mean of its divisors is an integer number (20497760190).

Almost surely, 2^81535534799 is an apocalyptic number.

81535534799 is a deficient number, since it is larger than the sum of its proper divisors (455505961).

81535534799 is a wasteful number, since it uses less digits than its factorization.

81535534799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455505960.

The product of its digits is 20412000, while the sum is 59.

The spelling of 81535534799 in words is "eighty-one billion, five hundred thirty-five million, five hundred thirty-four thousand, seven hundred ninety-nine".