81166475905 has 8 divisors (see below), whose sum is σ = 97717036032. Its totient is φ = 64721670768.

The previous prime is 81166475857. The next prime is 81166475917. The reversal of 81166475905 is 50957466118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81166475905 - 2¹³ = 81166467713 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26437057 + ... + 26440126.

It is an arithmetic number, because the mean of its divisors is an integer number (12214629504).

Almost surely, 2^81166475905 is an apocalyptic number.

It is an amenable number.

81166475905 is a deficient number, since it is larger than the sum of its proper divisors (16550560127).

81166475905 is a wasteful number, since it uses less digits than its factorization.

81166475905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52877495.

The product of its (nonzero) digits is 1814400, while the sum is 52.

The spelling of 81166475905 in words is "eighty-one billion, one hundred sixty-six million, four hundred seventy-five thousand, nine hundred five".