20117209 has 4 divisors (see below), whose sum is σ = 22991104. Its totient is φ = 17243316.

The previous prime is 20117179. The next prime is 20117231. The reversal of 20117209 is 90271102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90271102 = 2 ⋅45135551.

It is a cyclic number.

It is not a de Polignac number, because 20117209 - 2¹³ = 20109017 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20117209.

It is not an unprimeable number, because it can be changed into a prime (20117299) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1436937 + ... + 1436950.

It is an arithmetic number, because the mean of its divisors is an integer number (5747776).

Almost surely, 2^20117209 is an apocalyptic number.

It is an amenable number.

20117209 is a deficient number, since it is larger than the sum of its proper divisors (2873895).

20117209 is an equidigital number, since it uses as much as digits as its factorization.

20117209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2873894.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 20117209 is about 4485.2211762632. The cubic root of 20117209 is about 271.9709861281.

The spelling of 20117209 in words is "twenty million, one hundred seventeen thousand, two hundred nine".