81644107 has 4 divisors (see below), whose sum is σ = 82794096. Its totient is φ = 80494120.

The previous prime is 81644099. The next prime is 81644117. The reversal of 81644107 is 70144618.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 81644107 - 2³ = 81644099 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81644117) 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, 574888 + ... + 575029.

It is an arithmetic number, because the mean of its divisors is an integer number (20698524).

Almost surely, 2^81644107 is an apocalyptic number.

81644107 is a deficient number, since it is larger than the sum of its proper divisors (1149989).

81644107 is a wasteful number, since it uses less digits than its factorization.

81644107 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1149988.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 81644107 is about 9035.7128661772. The cubic root of 81644107 is about 433.8187124656.

The spelling of 81644107 in words is "eighty-one million, six hundred forty-four thousand, one hundred seven".