16509809 has 2 divisors, whose sum is σ = 16509810. Its totient is φ = 16509808.

The previous prime is 16509769. The next prime is 16509817. The reversal of 16509809 is 90890561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15626209 + 883600 = 3953^2 + 940^2 .

It is a cyclic number.

It is not a de Polignac number, because 16509809 - 2¹⁶ = 16444273 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (16509859) 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, 8254904 + 8254905.

It is an arithmetic number, because the mean of its divisors is an integer number (8254905).

Almost surely, 2^16509809 is an apocalyptic number.

It is an amenable number.

16509809 is a deficient number, since it is larger than the sum of its proper divisors (1).

16509809 is an equidigital number, since it uses as much as digits as its factorization.

16509809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 16509809 is about 4063.2264273604. The cubic root of 16509809 is about 254.6326069033.

The spelling of 16509809 in words is "sixteen million, five hundred nine thousand, eight hundred nine".