81165859 has 2 divisors, whose sum is σ = 81165860. Its totient is φ = 81165858.

The previous prime is 81165857. The next prime is 81165863. The reversal of 81165859 is 95856118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81165859 - 2¹ = 81165857 is a prime.

Together with 81165857, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81165857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40582929 + 40582930.

It is an arithmetic number, because the mean of its divisors is an integer number (40582930).

Almost surely, 2^81165859 is an apocalyptic number.

81165859 is a deficient number, since it is larger than the sum of its proper divisors (1).

81165859 is an equidigital number, since it uses as much as digits as its factorization.

81165859 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 86400, while the sum is 43.

The square root of 81165859 is about 9009.2096767697. The cubic root of 81165859 is about 432.9699908265.

The spelling of 81165859 in words is "eighty-one million, one hundred sixty-five thousand, eight hundred fifty-nine".