20909517 has 4 divisors (see below), whose sum is σ = 27879360. Its totient is φ = 13939676.

The previous prime is 20909503. The next prime is 20909533. The reversal of 20909517 is 71590902.

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.

It is a cyclic number.

It is not a de Polignac number, because 20909517 - 2⁶ = 20909453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20909587) 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, 3484917 + ... + 3484922.

It is an arithmetic number, because the mean of its divisors is an integer number (6969840).

Almost surely, 2^20909517 is an apocalyptic number.

It is an amenable number.

20909517 is a deficient number, since it is larger than the sum of its proper divisors (6969843).

20909517 is an equidigital number, since it uses as much as digits as its factorization.

20909517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6969842.

The product of its (nonzero) digits is 5670, while the sum is 33.

The square root of 20909517 is about 4572.6925328520. The cubic root of 20909517 is about 275.4955999662.

The spelling of 20909517 in words is "twenty million, nine hundred nine thousand, five hundred seventeen".