81809023 has 2 divisors, whose sum is σ = 81809024. Its totient is φ = 81809022.

The previous prime is 81809009. The next prime is 81809047. The reversal of 81809023 is 32090818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81809023 - 2⁹ = 81808511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81803023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40904511 + 40904512.

It is an arithmetic number, because the mean of its divisors is an integer number (40904512).

Almost surely, 2^81809023 is an apocalyptic number.

81809023 is a deficient number, since it is larger than the sum of its proper divisors (1).

81809023 is an equidigital number, since it uses as much as digits as its factorization.

81809023 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 81809023 is about 9044.8340504401. The cubic root of 81809023 is about 434.1106115879.

The spelling of 81809023 in words is "eighty-one million, eight hundred nine thousand, twenty-three".