81909511375 has 16 divisors (see below), whose sum is σ = 103898867904. Its totient is φ = 64453380000.

The previous prime is 81909511357. The next prime is 81909511379. The reversal of 81909511375 is 57311590918.

It is not a de Polignac number, because 81909511375 - 2²⁹ = 81372640463 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 (81909511379) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5363491 + ... + 5378740.

It is an arithmetic number, because the mean of its divisors is an integer number (6493679244).

Almost surely, 2^81909511375 is an apocalyptic number.

81909511375 is a deficient number, since it is larger than the sum of its proper divisors (21989356529).

81909511375 is a wasteful number, since it uses less digits than its factorization.

81909511375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10742307 (or 10742297 counting only the distinct ones).

The product of its (nonzero) digits is 340200, while the sum is 49.

The spelling of 81909511375 in words is "eighty-one billion, nine hundred nine million, five hundred eleven thousand, three hundred seventy-five".