85661 has 2 divisors, whose sum is σ = 85662. Its totient is φ = 85660.

The previous prime is 85643. The next prime is 85667. The reversal of 85661 is 16658.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52900 + 32761 = 230^2 + 181^2 .

It is a cyclic number.

It is not a de Polignac number, because 85661 - 2⁶ = 85597 is a prime.

It is a Chen prime.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 85661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (85667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42830 + 42831.

It is an arithmetic number, because the mean of its divisors is an integer number (42831).

2⁸⁵⁶⁶¹ is an apocalyptic number.

It is an amenable number.

85661 is a deficient number, since it is larger than the sum of its proper divisors (1).

85661 is an equidigital number, since it uses as much as digits as its factorization.

85661 is an evil number, because the sum of its binary digits is even.

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

The square root of 85661 is about 292.6790050550. The cubic root of 85661 is about 44.0819752783.

The spelling of 85661 in words is "eighty-five thousand, six hundred sixty-one".