20979645 has 16 divisors (see below), whose sum is σ = 33915840. Its totient is φ = 11073024.

The previous prime is 20979641. The next prime is 20979671. The reversal of 20979645 is 54697902.

It is not a de Polignac number, because 20979645 - 2² = 20979641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20979597 and 20979606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20979641) 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 15 ways as a sum of consecutive naturals, for example, 5755 + ... + 8664.

It is an arithmetic number, because the mean of its divisors is an integer number (2119740).

Almost surely, 2^20979645 is an apocalyptic number.

It is an amenable number.

20979645 is a deficient number, since it is larger than the sum of its proper divisors (12936195).

20979645 is a wasteful number, since it uses less digits than its factorization.

20979645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14524.

The product of its (nonzero) digits is 136080, while the sum is 42.

The square root of 20979645 is about 4580.3542439423. The cubic root of 20979645 is about 275.8032492957.

The spelling of 20979645 in words is "twenty million, nine hundred seventy-nine thousand, six hundred forty-five".