1688909 has 2 divisors, whose sum is σ = 1688910. Its totient is φ = 1688908.

The previous prime is 1688903. The next prime is 1688917. The reversal of 1688909 is 9098861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 896809 + 792100 = 947^2 + 890^2 .

It is an emirp because it is prime and its reverse (9098861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1688909 - 2⁴ = 1688893 is a prime.

It is a super-2 number, since 2×1688909² = 5704827220562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1688903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 844454 + 844455.

It is an arithmetic number, because the mean of its divisors is an integer number (844455).

2^1688909 is an apocalyptic number.

It is an amenable number.

1688909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1688909 is an equidigital number, since it uses as much as digits as its factorization.

1688909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104, while the sum is 41.

The square root of 1688909 is about 1299.5803168716. The cubic root of 1688909 is about 119.0882052067.

The spelling of 1688909 in words is "one million, six hundred eighty-eight thousand, nine hundred nine".