81538339209 has 32 divisors (see below), whose sum is σ = 114430771200. Its totient is φ = 51544164672.

The previous prime is 81538339193. The next prime is 81538339213. The reversal of 81538339209 is 90293383518.

It is not a de Polignac number, because 81538339209 - 2⁴ = 81538339193 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81538339219) 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, 13570884 + ... + 13576890.

It is an arithmetic number, because the mean of its divisors is an integer number (3575961600).

Almost surely, 2^81538339209 is an apocalyptic number.

It is an amenable number.

81538339209 is a deficient number, since it is larger than the sum of its proper divisors (32892431991).

81538339209 is a wasteful number, since it uses less digits than its factorization.

81538339209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7709.

The product of its (nonzero) digits is 1399680, while the sum is 51.

The spelling of 81538339209 in words is "eighty-one billion, five hundred thirty-eight million, three hundred thirty-nine thousand, two hundred nine".