21556115556 has 48 divisors (see below), whose sum is σ = 52293474240. Its totient is φ = 6905479680.

The previous prime is 21556115501. The next prime is 21556115593. The reversal of 21556115556 is 65551165512.

It is a super-2 number, since 2×21556115556² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 294001 + ... + 359928.

It is an arithmetic number, because the mean of its divisors is an integer number (1089447380).

Almost surely, 2^21556115556 is an apocalyptic number.

It is an amenable number.

21556115556 is an abundant number, since it is smaller than the sum of its proper divisors (30737358684).

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

21556115556 is a wasteful number, since it uses less digits than its factorization.

21556115556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 654044 (or 654042 counting only the distinct ones).

The product of its digits is 225000, while the sum is 42.

The spelling of 21556115556 in words is "twenty-one billion, five hundred fifty-six million, one hundred fifteen thousand, five hundred fifty-six".