688309 has 2 divisors, whose sum is σ = 688310. Its totient is φ = 688308.

The previous prime is 688297. The next prime is 688333. The reversal of 688309 is 903886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 485809 + 202500 = 697^2 + 450^2 .

It is a cyclic number.

It is not a de Polignac number, because 688309 - 2⁵ = 688277 is a prime.

It is an Ulam number.

688309 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344154 + 344155.

It is an arithmetic number, because the mean of its divisors is an integer number (344155).

2⁶⁸⁸³⁰⁹ is an apocalyptic number.

It is an amenable number.

688309 is a deficient number, since it is larger than the sum of its proper divisors (1).

688309 is an equidigital number, since it uses as much as digits as its factorization.

688309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 688309 is about 829.6438995135. The cubic root of 688309 is about 88.2933136228.

The spelling of 688309 in words is "six hundred eighty-eight thousand, three hundred nine".