81840923 has 16 divisors (see below), whose sum is σ = 90616320. Its totient is φ = 73567296.

The previous prime is 81840827. The next prime is 81840947. The reversal of 81840923 is 32904818.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81840923 - 2⁸ = 81840667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81840953) 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 15 ways as a sum of consecutive naturals, for example, 59186 + ... + 60552.

It is an arithmetic number, because the mean of its divisors is an integer number (5663520).

Almost surely, 2^81840923 is an apocalyptic number.

81840923 is a deficient number, since it is larger than the sum of its proper divisors (8775397).

81840923 is a wasteful number, since it uses less digits than its factorization.

81840923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1546.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 81840923 is about 9046.5973161184. The cubic root of 81840923 is about 434.1670288732.

The spelling of 81840923 in words is "eighty-one million, eight hundred forty thousand, nine hundred twenty-three".