20979936 has 72 divisors (see below), whose sum is σ = 60357024. Its totient is φ = 6912000.

The previous prime is 20979929. The next prime is 20979943. The reversal of 20979936 is 63997902.

It is an interprime number because it is at equal distance from previous prime (20979929) and next prime (20979943).

It is a tau number, because it is divible by the number of its divisors (72).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 20979891 and 20979900.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27561 + ... + 28311.

It is an arithmetic number, because the mean of its divisors is an integer number (838292).

Almost surely, 2^20979936 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20979936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30178512).

20979936 is an abundant number, since it is smaller than the sum of its proper divisors (39377088).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20979936 is a wasteful number, since it uses less digits than its factorization.

20979936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864 (or 853 counting only the distinct ones).

The product of its (nonzero) digits is 183708, while the sum is 45.

The square root of 20979936 is about 4580.3860099341. The cubic root of 20979936 is about 275.8045244741.

The spelling of 20979936 in words is "twenty million, nine hundred seventy-nine thousand, nine hundred thirty-six".