81566 has 8 divisors (see below), whose sum is σ = 129600. Its totient is φ = 38368.

The previous prime is 81563. The next prime is 81569. The reversal of 81566 is 66518.

It is an interprime number because it is at equal distance from previous prime (81563) and next prime (81569).

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

It is a plaindrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81563) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1166 + ... + 1233.

It is an arithmetic number, because the mean of its divisors is an integer number (16200).

2⁸¹⁵⁶⁶ is an apocalyptic number.

81566 is a deficient number, since it is larger than the sum of its proper divisors (48034).

81566 is a wasteful number, since it uses less digits than its factorization.

81566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2418.

The product of its digits is 1440, while the sum is 26.

The square root of 81566 is about 285.5976190377. The cubic root of 81566 is about 43.3680326934.

The spelling of 81566 in words is "eighty-one thousand, five hundred sixty-six".