81566885 has 8 divisors (see below), whose sum is σ = 97928736. Its totient is φ = 65221200.

The previous prime is 81566873. The next prime is 81566909. The reversal of 81566885 is 58866518.

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

It is not a de Polignac number, because 81566885 - 2⁴ = 81566869 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent 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, 18110 + ... + 22160.

It is an arithmetic number, because the mean of its divisors is an integer number (12241092).

Almost surely, 2^81566885 is an apocalyptic number.

It is an amenable number.

81566885 is a deficient number, since it is larger than the sum of its proper divisors (16361851).

81566885 is a wasteful number, since it uses less digits than its factorization.

81566885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8083.

The product of its digits is 460800, while the sum is 47.

The square root of 81566885 is about 9031.4387004508. The cubic root of 81566885 is about 433.6818954217.

The spelling of 81566885 in words is "eighty-one million, five hundred sixty-six thousand, eight hundred eighty-five".