20909579 has 4 divisors (see below), whose sum is σ = 21101520. Its totient is φ = 20717640.

The previous prime is 20909573. The next prime is 20909587. The reversal of 20909579 is 97590902.

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

It is a cyclic number.

It is not a de Polignac number, because 20909579 - 2⁴ = 20909563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20909573) 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, 95807 + ... + 96024.

It is an arithmetic number, because the mean of its divisors is an integer number (5275380).

Almost surely, 2^20909579 is an apocalyptic number.

20909579 is a deficient number, since it is larger than the sum of its proper divisors (191941).

20909579 is a wasteful number, since it uses less digits than its factorization.

20909579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 191940.

The product of its (nonzero) digits is 51030, while the sum is 41.

The square root of 20909579 is about 4572.6993122225. The cubic root of 20909579 is about 275.4958722618.

The spelling of 20909579 in words is "twenty million, nine hundred nine thousand, five hundred seventy-nine".