21555589104 has 480 divisors, whose sum is σ = 76435107840. Its totient is φ = 5748019200.

The previous prime is 21555589063. The next prime is 21555589163. The reversal of 21555589104 is 40198555512.

21555589104 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 558 + 91 + 0 + 4 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21555589104.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 24466744 + ... + 24467624.

It is an arithmetic number, because the mean of its divisors is an integer number (159239808).

Almost surely, 2^21555589104 is an apocalyptic number.

21555589104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21555589104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38217553920).

21555589104 is an abundant number, since it is smaller than the sum of its proper divisors (54879518736).

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

21555589104 is a wasteful number, since it uses less digits than its factorization.

21555589104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 971 (or 953 counting only the distinct ones).

The product of its (nonzero) digits is 360000, while the sum is 45.

The spelling of 21555589104 in words is "twenty-one billion, five hundred fifty-five million, five hundred eighty-nine thousand, one hundred four".