21556605543 has 16 divisors (see below), whose sum is σ = 31361433600. Its totient is φ = 13061954880.

The previous prime is 21556605541. The next prime is 21556605569. The reversal of 21556605543 is 34550665512.

It is not a de Polignac number, because 21556605543 - 2¹ = 21556605541 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21556605495 and 21556605504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556605541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 105123 + ... + 232731.

It is an arithmetic number, because the mean of its divisors is an integer number (1960089600).

Almost surely, 2^21556605543 is an apocalyptic number.

21556605543 is a deficient number, since it is larger than the sum of its proper divisors (9804828057).

21556605543 is a wasteful number, since it uses less digits than its factorization.

21556605543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132742.

The product of its (nonzero) digits is 540000, while the sum is 42.

The spelling of 21556605543 in words is "twenty-one billion, five hundred fifty-six million, six hundred five thousand, five hundred forty-three".