20979009 has 12 divisors (see below), whose sum is σ = 30730752. Its totient is φ = 13788600.

The previous prime is 20979001. The next prime is 20979017. The reversal of 20979009 is 90097902.

It is an interprime number because it is at equal distance from previous prime (20979001) and next prime (20979017).

It is not a de Polignac number, because 20979009 - 2³ = 20979001 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20979001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15777 + ... + 17054.

It is an arithmetic number, because the mean of its divisors is an integer number (2560896).

Almost surely, 2^20979009 is an apocalyptic number.

It is an amenable number.

20979009 is a deficient number, since it is larger than the sum of its proper divisors (9751743).

20979009 is a wasteful number, since it uses less digits than its factorization.

20979009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32908 (or 32905 counting only the distinct ones).

The product of its (nonzero) digits is 10206, while the sum is 36.

The square root of 20979009 is about 4580.2848164716. The cubic root of 20979009 is about 275.8004622666.

The spelling of 20979009 in words is "twenty million, nine hundred seventy-nine thousand, nine".