81475065823 has 4 divisors (see below), whose sum is σ = 81815965920. Its totient is φ = 81134165728.

The previous prime is 81475065811. The next prime is 81475065913. The reversal of 81475065823 is 32856057418.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81475065823 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 (81475065223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 170449690 + ... + 170450167.

It is an arithmetic number, because the mean of its divisors is an integer number (20453991480).

Almost surely, 2^81475065823 is an apocalyptic number.

81475065823 is a deficient number, since it is larger than the sum of its proper divisors (340900097).

81475065823 is a wasteful number, since it uses less digits than its factorization.

81475065823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340900096.

The product of its (nonzero) digits is 1612800, while the sum is 49.

The spelling of 81475065823 in words is "eighty-one billion, four hundred seventy-five million, sixty-five thousand, eight hundred twenty-three".