25989 has 4 divisors (see below), whose sum is σ = 34656.
Its totient is φ = 17324.
The previous prime is 25981. The next prime is 25997. The reversal of 25989 is 98952.
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 an interprime number because it is at equal distance from previous prime (25981) and next prime (25997).
It is a cyclic number.
It is not a de Polignac number, because 25989 - 23 = 25981 is a prime.
It is a D-number.
It is a nialpdrome in base 13.
It is a congruent number.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 25989.
It is not an unprimeable number, because it can be changed into a prime (25981) 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, 4329 + ... + 4334.
It is an arithmetic number, because the mean of its divisors is an integer number (8664).
225989 is an apocalyptic number.
It is an amenable number.
25989 is a deficient number, since it is larger than the sum of its proper divisors (8667).
25989 is an equidigital number, since it uses as much as digits as its factorization.
25989 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 8666.
The product of its digits is 6480, while the sum is 33.
The square root of 25989 is about 161.2110418055.
The cubic root of 25989 is about 29.6207822157.
The spelling of 25989 in words is "twenty-five thousand, nine hundred eighty-nine".