81571374409 has 4 divisors (see below), whose sum is σ = 93224427904. Its totient is φ = 69918320916.

The previous prime is 81571374349. The next prime is 81571374413. The reversal of 81571374409 is 90447317518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81571374409 - 2²⁵ = 81537819977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81571374439) 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, 5826526737 + ... + 5826526750.

It is an arithmetic number, because the mean of its divisors is an integer number (23306106976).

Almost surely, 2^81571374409 is an apocalyptic number.

It is an amenable number.

81571374409 is a deficient number, since it is larger than the sum of its proper divisors (11653053495).

81571374409 is a wasteful number, since it uses less digits than its factorization.

81571374409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11653053494.

The product of its (nonzero) digits is 846720, while the sum is 49.

The spelling of 81571374409 in words is "eighty-one billion, five hundred seventy-one million, three hundred seventy-four thousand, four hundred nine".