20900209 has 12 divisors (see below), whose sum is σ = 24184720. Its totient is φ = 17998200.

The previous prime is 20900189. The next prime is 20900221. The reversal of 20900209 is 90200902.

It is not a de Polignac number, because 20900209 - 2⁵ = 20900177 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20900209.

It is not an unprimeable number, because it can be changed into a prime (20900239) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2247 + ... + 6844.

Almost surely, 2^20900209 is an apocalyptic number.

It is an amenable number.

20900209 is a deficient number, since it is larger than the sum of its proper divisors (3284511).

20900209 is a wasteful number, since it uses less digits than its factorization.

20900209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9132 (or 9121 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 20900209 is about 4571.6746384667. The cubic root of 20900209 is about 275.4547143789.

Adding to 20900209 its reverse (90200902), we get a palindrome (111101111).

It can be divided in two parts, 20900 and 209, that multiplied together give a square (4368100 = 2090²).

The spelling of 20900209 in words is "twenty million, nine hundred thousand, two hundred nine".