21663011555533 has 4 divisors (see below), whose sum is σ = 21709799917888. Its totient is φ = 21616223193180.

The previous prime is 21663011555503. The next prime is 21663011555539. The reversal of 21663011555533 is 33555511036612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21663011555533 - 2²¹ = 21663009458381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21663011555539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23394180483 + ... + 23394181408.

It is an arithmetic number, because the mean of its divisors is an integer number (5427449979472).

Almost surely, 2^{21663011555533} is an apocalyptic number.

It is an amenable number.

21663011555533 is a deficient number, since it is larger than the sum of its proper divisors (46788362355).

21663011555533 is an equidigital number, since it uses as much as digits as its factorization.

21663011555533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46788362354.

The product of its (nonzero) digits is 1215000, while the sum is 46.

The spelling of 21663011555533 in words is "twenty-one trillion, six hundred sixty-three billion, eleven million, five hundred fifty-five thousand, five hundred thirty-three".