21606072768 has 336 divisors, whose sum is σ = 74176128000. Its totient is φ = 5882333184.

The previous prime is 21606072749. The next prime is 21606072779. The reversal of 21606072768 is 86727060612.

21606072768 is a `hidden beast` number, since 2 + 16 + 0 + 607 + 27 + 6 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-2 number, since 2×21606072768² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 9236143 + ... + 9238481.

Almost surely, 2^21606072768 is an apocalyptic number.

21606072768 is a gapful number since it is divisible by the number (28) 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 21606072768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37088064000).

21606072768 is an abundant number, since it is smaller than the sum of its proper divisors (52570055232).

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

21606072768 is a wasteful number, since it uses less digits than its factorization.

21606072768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2472 (or 2459 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 45.

The spelling of 21606072768 in words is "twenty-one billion, six hundred six million, seventy-two thousand, seven hundred sixty-eight".