81656 has 16 divisors (see below), whose sum is σ = 156600. Its totient is φ = 39904.

The previous prime is 81649. The next prime is 81667. The reversal of 81656 is 65618.

It is a super-3 number, since 3×81656³ = 1633373705845248, which contains 333 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 386 + ... + 558.

2⁸¹⁶⁵⁶ is an apocalyptic number.

It is an amenable number.

81656 is a deficient number, since it is larger than the sum of its proper divisors (74944).

81656 is a wasteful number, since it uses less digits than its factorization.

81656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238 (or 234 counting only the distinct ones).

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

The square root of 81656 is about 285.7551399363. The cubic root of 81656 is about 43.3839776062.

It can be divided in two parts, 81 and 656, that added together give a palindrome (737).

The spelling of 81656 in words is "eighty-one thousand, six hundred fifty-six".