66856 has 16 divisors (see below), whose sum is σ = 128340. Its totient is φ = 32640.

The previous prime is 66853. The next prime is 66863. The reversal of 66856 is 65866.

It can be written as a sum of positive squares in 2 ways, for example, as 62500 + 4356 = 250^2 + 66^2 .

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 420 + ... + 556.

2⁶⁶⁸⁵⁶ is an apocalyptic number.

It is an amenable number.

66856 is a deficient number, since it is larger than the sum of its proper divisors (61484).

66856 is a wasteful number, since it uses less digits than its factorization.

66856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204 (or 200 counting only the distinct ones).

The product of its digits is 8640, while the sum is 31.

The square root of 66856 is about 258.5652722235. The cubic root of 66856 is about 40.5863624754.

Subtracting from 66856 its reverse (65866), we obtain a triangular number (990 = T₄₄).

The spelling of 66856 in words is "sixty-six thousand, eight hundred fifty-six".