66689 has 6 divisors (see below), whose sum is σ = 77634. Its totient is φ = 57120.

The previous prime is 66683. The next prime is 66697. The reversal of 66689 is 98666.

It can be written as a sum of positive squares in only one way, i.e., 47089 + 19600 = 217^2 + 140^2 .

It is not a de Polignac number, because 66689 - 2¹⁶ = 1153 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 10 and base 13.

It is not an unprimeable number, because it can be changed into a prime (66683) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 632 + ... + 729.

It is an arithmetic number, because the mean of its divisors is an integer number (12939).

2⁶⁶⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

66689 is a deficient number, since it is larger than the sum of its proper divisors (10945).

66689 is a wasteful number, since it uses less digits than its factorization.

66689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1375 (or 1368 counting only the distinct ones).

The product of its digits is 15552, while the sum is 35.

The square root of 66689 is about 258.2421344398. The cubic root of 66689 is about 40.5525406598.

The spelling of 66689 in words is "sixty-six thousand, six hundred eighty-nine".