81909023 has 16 divisors (see below), whose sum is σ = 96155136. Its totient is φ = 68312160.

The previous prime is 81909011. The next prime is 81909071. The reversal of 81909023 is 32090918.

It is not a de Polignac number, because 81909023 - 2⁸ = 81908767 is a prime.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81909623) 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, 151133 + ... + 151673.

It is an arithmetic number, because the mean of its divisors is an integer number (6009696).

Almost surely, 2^81909023 is an apocalyptic number.

81909023 is a deficient number, since it is larger than the sum of its proper divisors (14246113).

81909023 is a wasteful number, since it uses less digits than its factorization.

81909023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1094.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 81909023 is about 9050.3603795650. The cubic root of 81909023 is about 434.2874192456.

The spelling of 81909023 in words is "eighty-one million, nine hundred nine thousand, twenty-three".