81566894 has 16 divisors (see below), whose sum is σ = 125053632. Its totient is φ = 39887328.

The previous prime is 81566873. The next prime is 81566909. The reversal of 81566894 is 49866518.

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, 38507 + ... + 40569.

It is an arithmetic number, because the mean of its divisors is an integer number (7815852).

Almost surely, 2^81566894 is an apocalyptic number.

81566894 is a deficient number, since it is larger than the sum of its proper divisors (43486738).

81566894 is a wasteful number, since it uses less digits than its factorization.

81566894 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2491.

The product of its digits is 414720, while the sum is 47.

The square root of 81566894 is about 9031.4391987102. The cubic root of 81566894 is about 433.6819113723.

The spelling of 81566894 in words is "eighty-one million, five hundred sixty-six thousand, eight hundred ninety-four".