20696209 has 4 divisors (see below), whose sum is σ = 21255604. Its totient is φ = 20136816.

The previous prime is 20696177. The next prime is 20696219. The reversal of 20696209 is 90269602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15429184 + 5267025 = 3928^2 + 2295^2 .

It is a cyclic number.

It is not a de Polignac number, because 20696209 - 2⁵ = 20696177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20696219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 279642 + ... + 279715.

It is an arithmetic number, because the mean of its divisors is an integer number (5313901).

Almost surely, 2^20696209 is an apocalyptic number.

It is an amenable number.

20696209 is a deficient number, since it is larger than the sum of its proper divisors (559395).

20696209 is an equidigital number, since it uses as much as digits as its factorization.

20696209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 559394.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 20696209 is about 4549.3086287919. The cubic root of 20696209 is about 274.5555752695. Note that the first 4 decimals are identical.

The spelling of 20696209 in words is "twenty million, six hundred ninety-six thousand, two hundred nine".