27989 has 4 divisors (see below), whose sum is σ = 30156. Its totient is φ = 25824.

The previous prime is 27983. The next prime is 27997. The reversal of 27989 is 98972.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3025 + 24964 = 55^2 + 158^2 .

It is a cyclic number.

It is not a de Polignac number, because 27989 - 2⁸ = 27733 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27983) 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, 1064 + ... + 1089.

It is an arithmetic number, because the mean of its divisors is an integer number (7539).

2²⁷⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

27989 is a deficient number, since it is larger than the sum of its proper divisors (2167).

27989 is a wasteful number, since it uses less digits than its factorization.

27989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2166.

The product of its digits is 9072, while the sum is 35.

The square root of 27989 is about 167.2991332912. The cubic root of 27989 is about 30.3619127124.

The spelling of 27989 in words is "twenty-seven thousand, nine hundred eighty-nine".