81938911 has 4 divisors (see below), whose sum is σ = 82126000. Its totient is φ = 81751824.

The previous prime is 81938893. The next prime is 81938917. The reversal of 81938911 is 11983918.

It is a happy number.

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 81938911 - 2¹⁹ = 81414623 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 (81938917) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 92886 + ... + 93763.

It is an arithmetic number, because the mean of its divisors is an integer number (20531500).

Almost surely, 2^81938911 is an apocalyptic number.

81938911 is a deficient number, since it is larger than the sum of its proper divisors (187089).

81938911 is a wasteful number, since it uses less digits than its factorization.

81938911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187088.

The product of its digits is 15552, while the sum is 40.

The square root of 81938911 is about 9052.0114339300. The cubic root of 81938911 is about 434.3402355836.

The spelling of 81938911 in words is "eighty-one million, nine hundred thirty-eight thousand, nine hundred eleven".