20806856 has 32 divisors (see below), whose sum is σ = 45324480. Its totient is φ = 8769600.

The previous prime is 20806847. The next prime is 20806867. The reversal of 20806856 is 65860802.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 371 + ... + 6461.

It is an arithmetic number, because the mean of its divisors is an integer number (1416390).

Almost surely, 2^20806856 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 20806856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22662240).

20806856 is an abundant number, since it is smaller than the sum of its proper divisors (24517624).

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

20806856 is a wasteful number, since it uses less digits than its factorization.

20806856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6165 (or 6161 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 20806856 is about 4561.4532771914. The cubic root of 20806856 is about 275.0439863524.

The spelling of 20806856 in words is "twenty million, eight hundred six thousand, eight hundred fifty-six".