81564823105 has 16 divisors (see below), whose sum is σ = 98942505984. Its totient is φ = 64542804480.

The previous prime is 81564823091. The next prime is 81564823121. The reversal of 81564823105 is 50132846518.

It is not a de Polignac number, because 81564823105 - 2⁹ = 81564822593 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 831904 + ... + 924766.

It is an arithmetic number, because the mean of its divisors is an integer number (6183906624).

Almost surely, 2^81564823105 is an apocalyptic number.

It is an amenable number.

81564823105 is a deficient number, since it is larger than the sum of its proper divisors (17377682879).

81564823105 is a wasteful number, since it uses less digits than its factorization.

81564823105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94776.

The product of its (nonzero) digits is 230400, while the sum is 43.

The spelling of 81564823105 in words is "eighty-one billion, five hundred sixty-four million, eight hundred twenty-three thousand, one hundred five".