20992209 has 16 divisors (see below), whose sum is σ = 32853888. Its totient is φ = 11670912.

The previous prime is 20992193. The next prime is 20992217. The reversal of 20992209 is 90229902.

It is not a de Polignac number, because 20992209 - 2⁴ = 20992193 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20992209.

It is not an unprimeable number, because it can be changed into a prime (20992249) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12732 + ... + 14285.

It is an arithmetic number, because the mean of its divisors is an integer number (2053368).

Almost surely, 2^20992209 is an apocalyptic number.

It is an amenable number.

20992209 is a deficient number, since it is larger than the sum of its proper divisors (11861679).

20992209 is a wasteful number, since it uses less digits than its factorization.

20992209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27064.

The product of its (nonzero) digits is 5832, while the sum is 33.

The square root of 20992209 is about 4581.7255483060. The cubic root of 20992209 is about 275.8582947222.

Adding to 20992209 its reverse (90229902), we get a palindrome (111222111).

The spelling of 20992209 in words is "twenty million, nine hundred ninety-two thousand, two hundred nine".