25666 has 8 divisors (see below), whose sum is σ = 39564. Its totient is φ = 12480.

The previous prime is 25657. The next prime is 25667. The reversal of 25666 is 66652.

25666 is nontrivially palindromic in base 5.

It can be written as a sum of positive squares in 2 ways, for example, as 16641 + 9025 = 129^2 + 95^2 .

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

It is a plaindrome in base 10.

It is a nialpdrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 25666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75 + ... + 238.

2²⁵⁶⁶⁶ is an apocalyptic number.

25666 is a deficient number, since it is larger than the sum of its proper divisors (13898).

25666 is a wasteful number, since it uses less digits than its factorization.

25666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356.

The product of its digits is 2160, while the sum is 25.

The square root of 25666 is about 160.2061172365. The cubic root of 25666 is about 29.4975579708.

The spelling of 25666 in words is "twenty-five thousand, six hundred sixty-six".