689821 has 6 divisors (see below), whose sum is σ = 758366. Its totient is φ = 627000.

The previous prime is 689807. The next prime is 689827. The reversal of 689821 is 128986.

689821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 662596 + 27225 = 814^2 + 165^2 .

It is not a de Polignac number, because 689821 - 2⁵ = 689789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (689827) 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, 2730 + ... + 2971.

2⁶⁸⁹⁸²¹ is an apocalyptic number.

It is an amenable number.

689821 is a deficient number, since it is larger than the sum of its proper divisors (68545).

689821 is a wasteful number, since it uses less digits than its factorization.

689821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5723 (or 5712 counting only the distinct ones).

The product of its digits is 6912, while the sum is 34.

The square root of 689821 is about 830.5546339646. The cubic root of 689821 is about 88.3579172902.

It can be divided in two parts, 68 and 9821, that added together give a palindrome (9889).

The spelling of 689821 in words is "six hundred eighty-nine thousand, eight hundred twenty-one".