21556661050000 has 60 divisors (see below), whose sum is σ = 52204197319092. Its totient is φ = 8622664400000.

The previous prime is 21556661049997. The next prime is 21556661050013. The reversal of 21556661050000 is 5016665512.

It can be written as a sum of positive squares in 6 ways, for example, as 19765635572736 + 1791025477264 = 4445856^2 + 1338292^2 .

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 215516611 + ... + 215616610.

Almost surely, 2^{21556661050000} is an apocalyptic number.

21556661050000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21556661050000 is an abundant number, since it is smaller than the sum of its proper divisors (30647536269092).

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

21556661050000 is an frugal number, since it uses more digits than its factorization.

21556661050000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431133254 (or 431133228 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 37.

The spelling of 21556661050000 in words is "twenty-one trillion, five hundred fifty-six billion, six hundred sixty-one million, fifty thousand".