21808708736256 has 324 divisors, whose sum is σ = 68184442872000. Its totient is φ = 6700952973312.

The previous prime is 21808708736251. The next prime is 21808708736281. The reversal of 21808708736256 is 65263780780812.

21808708736256 is a `hidden beast` number, since 2 + 1 + 80 + 8 + 70 + 87 + 362 + 56 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21808708736193 and 21808708736202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808708736251) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 279922395 + ... + 280000293.

Almost surely, 2^{21808708736256} is an apocalyptic number.

21808708736256 is a gapful number since it is divisible by the number (26) 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 21808708736256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34092221436000).

21808708736256 is an abundant number, since it is smaller than the sum of its proper divisors (46375734135744).

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

21808708736256 is a wasteful number, since it uses less digits than its factorization.

21808708736256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78666 (or 78636 counting only the distinct ones).

The product of its (nonzero) digits is 54190080, while the sum is 63.

The spelling of 21808708736256 in words is "twenty-one trillion, eight hundred eight billion, seven hundred eight million, seven hundred thirty-six thousand, two hundred fifty-six".