81436868139 has 32 divisors (see below), whose sum is σ = 119307976704. Its totient is φ = 49000424480.

The previous prime is 81436868129. The next prime is 81436868141. The reversal of 81436868139 is 93186863418.

It is a cyclic number.

It is not a de Polignac number, because 81436868139 - 2¹³ = 81436859947 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81436868129) 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, 4747432 + ... + 4764554.

It is an arithmetic number, because the mean of its divisors is an integer number (3728374272).

Almost surely, 2^81436868139 is an apocalyptic number.

81436868139 is a deficient number, since it is larger than the sum of its proper divisors (37871108565).

81436868139 is a wasteful number, since it uses less digits than its factorization.

81436868139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18167.

The product of its digits is 5971968, while the sum is 57.

The spelling of 81436868139 in words is "eighty-one billion, four hundred thirty-six million, eight hundred sixty-eight thousand, one hundred thirty-nine".