20821712256 has 160 divisors (see below), whose sum is σ = 62125925400. Its totient is φ = 6922561536.

The previous prime is 20821712239. The next prime is 20821712257. The reversal of 20821712256 is 65221712802.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 20821712256.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20821712257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4341796 + ... + 4346588.

Almost surely, 2^20821712256 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 20821712256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31062962700).

20821712256 is an abundant number, since it is smaller than the sum of its proper divisors (41304213144).

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

20821712256 is an equidigital number, since it uses as much as digits as its factorization.

20821712256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5238 (or 5217 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The spelling of 20821712256 in words is "twenty billion, eight hundred twenty-one million, seven hundred twelve thousand, two hundred fifty-six".