21655211663544 has 32 divisors (see below), whose sum is σ = 54823320672000. Its totient is φ = 7127031686112.

The previous prime is 21655211663521. The next prime is 21655211663593. The reversal of 21655211663544 is 44536611255612.

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, 5710760674 + ... + 5710764465.

It is an arithmetic number, because the mean of its divisors is an integer number (1713228771000).

Almost surely, 2^{21655211663544} is an apocalyptic number.

21655211663544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21655211663544 is an abundant number, since it is smaller than the sum of its proper divisors (33168109008456).

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

21655211663544 is a wasteful number, since it uses less digits than its factorization.

21655211663544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11421525227 (or 11421525223 counting only the distinct ones).

The product of its digits is 5184000, while the sum is 51.

The spelling of 21655211663544 in words is "twenty-one trillion, six hundred fifty-five billion, two hundred eleven million, six hundred sixty-three thousand, five hundred forty-four".