81166785 has 24 divisors (see below), whose sum is σ = 151070976. Its totient is φ = 37104480.

The previous prime is 81166769. The next prime is 81166807. The reversal of 81166785 is 58766118.

It is not a de Polignac number, because 81166785 - 2⁴ = 81166769 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 54481 + ... + 55950.

It is an arithmetic number, because the mean of its divisors is an integer number (6294624).

Almost surely, 2^81166785 is an apocalyptic number.

It is an amenable number.

81166785 is a deficient number, since it is larger than the sum of its proper divisors (69904191).

81166785 is a wasteful number, since it uses less digits than its factorization.

81166785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110453 (or 110446 counting only the distinct ones).

The product of its digits is 80640, while the sum is 42.

The square root of 81166785 is about 9009.2610684784. The cubic root of 81166785 is about 432.9716373673.

The spelling of 81166785 in words is "eighty-one million, one hundred sixty-six thousand, seven hundred eighty-five".