688909 has 8 divisors (see below), whose sum is σ = 748440. Its totient is φ = 630336.

The previous prime is 688907. The next prime is 688939. The reversal of 688909 is 909886.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 44100 + 644809 = 210^2 + 803^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 688909 - 2¹ = 688907 is a prime.

It is a super-2 number, since 2×688909² = 949191220562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2427 + ... + 2695.

It is an arithmetic number, because the mean of its divisors is an integer number (93555).

2⁶⁸⁸⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

688909 is a deficient number, since it is larger than the sum of its proper divisors (59531).

688909 is a wasteful number, since it uses less digits than its factorization.

688909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 479.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 688909 is about 830.0054216690. The cubic root of 688909 is about 88.3189613104.

The spelling of 688909 in words is "six hundred eighty-eight thousand, nine hundred nine".