85681 has 4 divisors (see below), whose sum is σ = 87552. Its totient is φ = 83812.

The previous prime is 85669. The next prime is 85691. The reversal of 85681 is 18658.

It is a happy number.

It is the 120-th star number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 85681 - 2¹³ = 77489 is a prime.

It is a super-2 number, since 2×85681² = 14682467522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 865 + ... + 958.

It is an arithmetic number, because the mean of its divisors is an integer number (21888).

2⁸⁵⁶⁸¹ is an apocalyptic number.

It is an amenable number.

85681 is a deficient number, since it is larger than the sum of its proper divisors (1871).

85681 is a wasteful number, since it uses less digits than its factorization.

85681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1870.

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

The square root of 85681 is about 292.7131701854. The cubic root of 85681 is about 44.0854057422.

The spelling of 85681 in words is "eighty-five thousand, six hundred eighty-one".