680689 has 4 divisors (see below), whose sum is σ = 699124. Its totient is φ = 662256.

The previous prime is 680681. The next prime is 680707. The reversal of 680689 is 986086.

680689 = 57² + 58² + ... + 130².

680689 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 986086 = 2 ⋅493043.

It can be written as a sum of positive squares in 2 ways, for example, as 613089 + 67600 = 783^2 + 260^2 .

It is a cyclic number.

It is not a de Polignac number, because 680689 - 2³ = 680681 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 18397 = 680689 / (6 + 8 + 0 + 6 + 8 + 9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (680681) 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, 9162 + ... + 9235.

It is an arithmetic number, because the mean of its divisors is an integer number (174781).

2⁶⁸⁰⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

680689 is a deficient number, since it is larger than the sum of its proper divisors (18435).

680689 is a wasteful number, since it uses less digits than its factorization.

680689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18434.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 680689 is about 825.0387869670. The cubic root of 680689 is about 87.9662835711.

It can be divided in two parts, 680 and 689, that added together give a square (1369 = 37²).

The spelling of 680689 in words is "six hundred eighty thousand, six hundred eighty-nine".