21663365556664 has 32 divisors (see below), whose sum is σ = 44033025284640. Its totient is φ = 9932261328000.

The previous prime is 21663365556619. The next prime is 21663365556683. The reversal of 21663365556664 is 46665556336612.

It is a super-2 number, since 2×21663365556664² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21663365556596 and 21663365556605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 689724667 + ... + 689756074.

It is an arithmetic number, because the mean of its divisors is an integer number (1376032040145).

Almost surely, 2^{21663365556664} is an apocalyptic number.

It is an amenable number.

21663365556664 is an abundant number, since it is smaller than the sum of its proper divisors (22369659727976).

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

21663365556664 is a wasteful number, since it uses less digits than its factorization.

21663365556664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1379480911 (or 1379480907 counting only the distinct ones).

The product of its digits is 419904000, while the sum is 64.

The spelling of 21663365556664 in words is "twenty-one trillion, six hundred sixty-three billion, three hundred sixty-five million, five hundred fifty-six thousand, six hundred sixty-four".