20816009 has 2 divisors, whose sum is σ = 20816010. Its totient is φ = 20816008.

The previous prime is 20815981. The next prime is 20816021. The reversal of 20816009 is 90061802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15976009 + 4840000 = 3997^2 + 2200^2 .

It is a cyclic number.

It is not a de Polignac number, because 20816009 - 2¹⁶ = 20750473 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20816099) 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, 10408004 + 10408005.

It is an arithmetic number, because the mean of its divisors is an integer number (10408005).

Almost surely, 2^20816009 is an apocalyptic number.

It is an amenable number.

20816009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20816009 is an equidigital number, since it uses as much as digits as its factorization.

20816009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 20816009 is about 4562.4564655457. The cubic root of 20816009 is about 275.0843113387.

The spelling of 20816009 in words is "twenty million, eight hundred sixteen thousand, nine".