23661 has 12 divisors (see below), whose sum is σ = 37440. Its totient is φ = 14280.

The previous prime is 23633. The next prime is 23663. The reversal of 23661 is 16632.

It is a happy number.

23661 is a `hidden beast` number, since 2 + 3 + 661 = 666.

It is not a de Polignac number, because 23661 - 2⁵ = 23629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23663) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21 + ... + 218.

It is an arithmetic number, because the mean of its divisors is an integer number (3120).

2²³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

23661 is a deficient number, since it is larger than the sum of its proper divisors (13779).

23661 is a wasteful number, since it uses less digits than its factorization.

23661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256 (or 253 counting only the distinct ones).

The product of its digits is 216, while the sum is 18.

The square root of 23661 is about 153.8213249195. The cubic root of 23661 is about 28.7085350586.

It can be divided in two parts, 2 and 3661, that added together give a palindrome (3663).

The spelling of 23661 in words is "twenty-three thousand, six hundred sixty-one".