2689 has 2 divisors, whose sum is σ = 2690.
Its totient is φ = 2688.
The previous prime is 2687. The next prime is 2693. The reversal of 2689 is 9862.
Adding to 2689 its product of digits (864), we get a palindrome (3553).
It can be divided in two parts, 2 and 689, that multiplied together give a triangular number (1378 = T52).
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 1600 + 1089 = 40^2 + 33^2
It is a cyclic number.
It is not a de Polignac number, because 2689 - 21 = 2687 is a prime.
Together with 2687, it forms a pair of twin primes.
2689 is a lucky number.
It is a plaindrome in base 10 and base 13.
It is a nialpdrome in base 14 and base 16.
It is not a weakly prime, because it can be changed into another prime (2683) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1344 + 1345.
It is an arithmetic number, because the mean of its divisors is an integer number (1345).
It is a Proth number, since it is equal to 21 ⋅ 27 + 1 and 21 < 27.
It is an amenable number.
2689 is a deficient number, since it is larger than the sum of its proper divisors (1).
2689 is an equidigital number, since it uses as much as digits as its factorization.
2689 is an evil number, because the sum of its binary digits is even.
The product of its digits is 864, while the sum is 25.
The square root of 2689 is about 51.8555686499.
The cubic root of 2689 is about 13.9058305853.
The spelling of 2689 in words is "two thousand, six hundred eighty-nine".