20979021 has 16 divisors (see below), whose sum is σ = 33651200. Its totient is φ = 11356848.

The previous prime is 20979019. The next prime is 20979029. The reversal of 20979021 is 12097902.

It is not a de Polignac number, because 20979021 - 2¹ = 20979019 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20979021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20979029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25891 + ... + 26688.

It is an arithmetic number, because the mean of its divisors is an integer number (2103200).

Almost surely, 2^20979021 is an apocalyptic number.

20979021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20979021 is a deficient number, since it is larger than the sum of its proper divisors (12672179).

20979021 is a wasteful number, since it uses less digits than its factorization.

20979021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52608.

The product of its (nonzero) digits is 2268, while the sum is 30.

The square root of 20979021 is about 4580.2861264336. The cubic root of 20979021 is about 275.8005148526.

The spelling of 20979021 in words is "twenty million, nine hundred seventy-nine thousand, twenty-one".