25566 has 8 divisors (see below), whose sum is σ = 51144. Its totient is φ = 8520.

The previous prime is 25561. The next prime is 25577. The reversal of 25566 is 66552.

It is a sphenic number, since it is the product of 3 distinct primes.

25566 is an admirable number.

It is a Curzon number.

It is a plaindrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25561) 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, 2125 + ... + 2136.

It is an arithmetic number, because the mean of its divisors is an integer number (6393).

2²⁵⁵⁶⁶ is an apocalyptic number.

25566 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25572).

25566 is a wasteful number, since it uses less digits than its factorization.

25566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4266.

The product of its digits is 1800, while the sum is 24.

The square root of 25566 is about 159.8937146982. The cubic root of 25566 is about 29.4591985970.

The spelling of 25566 in words is "twenty-five thousand, five hundred sixty-six".