20939856 has 120 divisors (see below), whose sum is σ = 65308320. Its totient is φ = 5757696.

The previous prime is 20939837. The next prime is 20939857. The reversal of 20939856 is 65893902.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20939857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 68055 + ... + 68361.

It is an arithmetic number, because the mean of its divisors is an integer number (544236).

Almost surely, 2^20939856 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 20939856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32654160).

20939856 is an abundant number, since it is smaller than the sum of its proper divisors (44368464).

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

20939856 is a wasteful number, since it uses less digits than its factorization.

20939856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361 (or 348 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 42.

The square root of 20939856 is about 4576.0087412504. The cubic root of 20939856 is about 275.6287804974.

The spelling of 20939856 in words is "twenty million, nine hundred thirty-nine thousand, eight hundred fifty-six".