688109309 has 2 divisors, whose sum is σ = 688109310. Its totient is φ = 688109308.

The previous prime is 688109299. The next prime is 688109369. The reversal of 688109309 is 903901886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 490622500 + 197486809 = 22150^2 + 14053^2 .

It is a cyclic number.

It is not a de Polignac number, because 688109309 - 2⁴ = 688109293 is a prime.

It is a super-2 number, since 2×688109309² = 946988842264914962, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 688109309.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688109369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344054654 + 344054655.

It is an arithmetic number, because the mean of its divisors is an integer number (344054655).

Almost surely, 2^688109309 is an apocalyptic number.

It is an amenable number.

688109309 is a deficient number, since it is larger than the sum of its proper divisors (1).

688109309 is an equidigital number, since it uses as much as digits as its factorization.

688109309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 44.

The square root of 688109309 is about 26231.8376977291. The cubic root of 688109309 is about 882.8477429650.

The spelling of 688109309 in words is "six hundred eighty-eight million, one hundred nine thousand, three hundred nine".