81856 has 14 divisors (see below), whose sum is σ = 162560. Its totient is φ = 40896.

The previous prime is 81853. The next prime is 81869. The reversal of 81856 is 65818.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81853) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 576 + ... + 703.

2⁸¹⁸⁵⁶ is an apocalyptic number.

It is an amenable number.

81856 is a deficient number, since it is larger than the sum of its proper divisors (80704).

81856 is a wasteful number, since it uses less digits than its factorization.

81856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1291 (or 1281 counting only the distinct ones).

The product of its digits is 1920, while the sum is 28.

The square root of 81856 is about 286.1048758760. The cubic root of 81856 is about 43.4193688455.

The spelling of 81856 in words is "eighty-one thousand, eight hundred fifty-six".