8661 has 4 divisors (see below), whose sum is σ = 11552. Its totient is φ = 5772.

The previous prime is 8647. The next prime is 8663. The reversal of 8661 is 1668.

8661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 8661 - 2⁵ = 8629 is a prime.

It is a D-number.

It is a Duffinian number.

8661 is a lucky number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1441 + ... + 1446.

It is an arithmetic number, because the mean of its divisors is an integer number (2888).

2⁸⁶⁶¹ is an apocalyptic number.

It is an amenable number.

8661 is a deficient number, since it is larger than the sum of its proper divisors (2891).

8661 is a wasteful number, since it uses less digits than its factorization.

8661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2890.

The product of its digits is 288, while the sum is 21.

The square root of 8661 is about 93.0644937664. The cubic root of 8661 is about 20.5363226753.

The spelling of 8661 in words is "eight thousand, six hundred sixty-one".