20809685 has 8 divisors (see below), whose sum is σ = 26892600. Its totient is φ = 15367104.

The previous prime is 20809669. The next prime is 20809699. The reversal of 20809685 is 58690802.

It can be written as a sum of positive squares in 4 ways, for example, as 361201 + 20448484 = 601^2 + 4522^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20809685 - 2⁴ = 20809669 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 160010 + ... + 160139.

It is an arithmetic number, because the mean of its divisors is an integer number (3361575).

Almost surely, 2^20809685 is an apocalyptic number.

It is an amenable number.

20809685 is a deficient number, since it is larger than the sum of its proper divisors (6082915).

20809685 is a wasteful number, since it uses less digits than its factorization.

20809685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320167.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 20809685 is about 4561.7633651911. The cubic root of 20809685 is about 275.0564512210.

The spelling of 20809685 in words is "twenty million, eight hundred nine thousand, six hundred eighty-five".