81078923 has 4 divisors (see below), whose sum is σ = 82608768. Its totient is φ = 79549080.

The previous prime is 81078917. The next prime is 81078953. The reversal of 81078923 is 32987018.

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 81078923 - 2⁶ = 81078859 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (81078953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 764843 + ... + 764948.

It is an arithmetic number, because the mean of its divisors is an integer number (20652192).

Almost surely, 2^81078923 is an apocalyptic number.

81078923 is a deficient number, since it is larger than the sum of its proper divisors (1529845).

81078923 is a wasteful number, since it uses less digits than its factorization.

81078923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1529844.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 81078923 is about 9004.3835435859. The cubic root of 81078923 is about 432.8153522200.

The spelling of 81078923 in words is "eighty-one million, seventy-eight thousand, nine hundred twenty-three".