81641011 has 4 divisors (see below), whose sum is σ = 84274624. Its totient is φ = 79007400.

The previous prime is 81640991. The next prime is 81641017. The reversal of 81641011 is 11014618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11014618 = 2 ⋅5507309.

It is a cyclic number.

It is not a de Polignac number, because 81641011 - 2⁷ = 81640883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81641017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1316760 + ... + 1316821.

It is an arithmetic number, because the mean of its divisors is an integer number (21068656).

Almost surely, 2^81641011 is an apocalyptic number.

81641011 is a deficient number, since it is larger than the sum of its proper divisors (2633613).

81641011 is a wasteful number, since it uses less digits than its factorization.

81641011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2633612.

The product of its (nonzero) digits is 192, while the sum is 22.

The square root of 81641011 is about 9035.5415443680. The cubic root of 81641011 is about 433.8132288295.

Adding to 81641011 its reverse (11014618), we get a palindrome (92655629).

The spelling of 81641011 in words is "eighty-one million, six hundred forty-one thousand, eleven".