21663220608 has 224 divisors, whose sum is σ = 66802411200. Its totient is φ = 6987202560.

The previous prime is 21663220591. The next prime is 21663220609. The reversal of 21663220608 is 80602236612.

21663220608 is a `hidden beast` number, since 2 + 16 + 6 + 32 + 2 + 0 + 608 = 666.

It is a super-2 number, since 2×21663220608² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21663220609) 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 27 ways as a sum of consecutive naturals, for example, 2888928 + ... + 2896416.

It is an arithmetic number, because the mean of its divisors is an integer number (298225050).

Almost surely, 2^21663220608 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 21663220608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33401205600).

21663220608 is an abundant number, since it is smaller than the sum of its proper divisors (45139190592).

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

21663220608 is an frugal number, since it uses more digits than its factorization.

21663220608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7552 (or 7525 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The spelling of 21663220608 in words is "twenty-one billion, six hundred sixty-three million, two hundred twenty thousand, six hundred eight".