81856207823 has 8 divisors (see below), whose sum is σ = 90996479616. Its totient is φ = 73122170400.

The previous prime is 81856207787. The next prime is 81856207831. The reversal of 81856207823 is 32870265818.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81856207823 - 2²² = 81852013519 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 (81856207123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 101558168 + ... + 101558973.

It is an arithmetic number, because the mean of its divisors is an integer number (11374559952).

Almost surely, 2^81856207823 is an apocalyptic number.

81856207823 is a deficient number, since it is larger than the sum of its proper divisors (9140271793).

81856207823 is a wasteful number, since it uses less digits than its factorization.

81856207823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203117185.

The product of its (nonzero) digits is 1290240, while the sum is 50.

The spelling of 81856207823 in words is "eighty-one billion, eight hundred fifty-six million, two hundred seven thousand, eight hundred twenty-three".