21533205500 has 48 divisors (see below), whose sum is σ = 47127225600. Its totient is φ = 8595204800.

The previous prime is 21533205497. The next prime is 21533205527. The reversal of 21533205500 is 550233512.

It is a self number, because there is not a number n which added to its sum of digits gives 21533205500.

It is a congruent number.

It is an unprimeable number.

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, 194546 + ... + 284454.

It is an arithmetic number, because the mean of its divisors is an integer number (981817200).

Almost surely, 2^21533205500 is an apocalyptic number.

21533205500 is a gapful number since it is divisible by the number (20) 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 21533205500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23563612800).

21533205500 is an abundant number, since it is smaller than the sum of its proper divisors (25594020100).

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

21533205500 is a wasteful number, since it uses less digits than its factorization.

21533205500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90407 (or 90395 counting only the distinct ones).

The product of its (nonzero) digits is 4500, while the sum is 26.

The spelling of 21533205500 in words is "twenty-one billion, five hundred thirty-three million, two hundred five thousand, five hundred".