81812923 has 4 divisors (see below), whose sum is σ = 81839160. Its totient is φ = 81786688.

The previous prime is 81812921. The next prime is 81812933. The reversal of 81812923 is 32921818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32921818 = 2 ⋅16460909.

It is a cyclic number.

It is not a de Polignac number, because 81812923 - 2¹ = 81812921 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81812921) 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, 7693 + ... + 14926.

It is an arithmetic number, because the mean of its divisors is an integer number (20459790).

Almost surely, 2^81812923 is an apocalyptic number.

81812923 is a deficient number, since it is larger than the sum of its proper divisors (26237).

81812923 is a wasteful number, since it uses less digits than its factorization.

81812923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26236.

The product of its digits is 6912, while the sum is 34.

The square root of 81812923 is about 9045.0496405492. The cubic root of 81812923 is about 434.1175097858.

The spelling of 81812923 in words is "eighty-one million, eight hundred twelve thousand, nine hundred twenty-three".