20856220 has 96 divisors (see below), whose sum is σ = 56609280. Its totient is φ = 6263040.

The previous prime is 20856181. The next prime is 20856221. The reversal of 20856220 is 2265802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20856221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 44427 + ... + 44893.

It is an arithmetic number, because the mean of its divisors is an integer number (589680).

Almost surely, 2^20856220 is an apocalyptic number.

20856220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20856220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28304640).

20856220 is an abundant number, since it is smaller than the sum of its proper divisors (35753060).

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

20856220 is a wasteful number, since it uses less digits than its factorization.

20856220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523 (or 521 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 20856220 is about 4566.8610664219. The cubic root of 20856220 is about 275.2613273444.

The spelling of 20856220 in words is "twenty million, eight hundred fifty-six thousand, two hundred twenty".