81723823 has 4 divisors (see below), whose sum is σ = 82063168. Its totient is φ = 81384480.

The previous prime is 81723821. The next prime is 81723833. The reversal of 81723823 is 32832718.

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

It is a cyclic number.

It is not a de Polignac number, because 81723823 - 2¹ = 81723821 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 (81723821) 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, 169311 + ... + 169792.

It is an arithmetic number, because the mean of its divisors is an integer number (20515792).

Almost surely, 2^81723823 is an apocalyptic number.

81723823 is a deficient number, since it is larger than the sum of its proper divisors (339345).

81723823 is a wasteful number, since it uses less digits than its factorization.

81723823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339344.

The product of its digits is 16128, while the sum is 34.

The square root of 81723823 is about 9040.1229527037. The cubic root of 81723823 is about 433.9598577552.

The spelling of 81723823 in words is "eighty-one million, seven hundred twenty-three thousand, eight hundred twenty-three".