688609 has 4 divisors (see below), whose sum is σ = 698116. Its totient is φ = 679104.

The previous prime is 688591. The next prime is 688621. The reversal of 688609 is 906886.

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 435600 + 253009 = 660^2 + 503^2 .

It is a cyclic number.

It is not a de Polignac number, because 688609 - 2⁹ = 688097 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 (688669) 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, 4644 + ... + 4789.

It is an arithmetic number, because the mean of its divisors is an integer number (174529).

2⁶⁸⁸⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

688609 is a deficient number, since it is larger than the sum of its proper divisors (9507).

688609 is an equidigital number, since it uses as much as digits as its factorization.

688609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9506.

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

The square root of 688609 is about 829.8246802789. The cubic root of 688609 is about 88.3061393289.

The spelling of 688609 in words is "six hundred eighty-eight thousand, six hundred nine".