21608816256 has 128 divisors (see below), whose sum is σ = 65133446400. Its totient is φ = 7049631744.

The previous prime is 21608816249. The next prime is 21608816269. The reversal of 21608816256 is 65261880612.

21608816256 is a `hidden beast` number, since 2 + 1 + 608 + 8 + 16 + 25 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 95916 + ... + 228948.

It is an arithmetic number, because the mean of its divisors is an integer number (508855050).

Almost surely, 2^21608816256 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 21608816256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32566723200).

21608816256 is an abundant number, since it is smaller than the sum of its proper divisors (43524630144).

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

21608816256 is a wasteful number, since it uses less digits than its factorization.

21608816256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133103 (or 133085 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The spelling of 21608816256 in words is "twenty-one billion, six hundred eight million, eight hundred sixteen thousand, two hundred fifty-six".