21043543500 has 384 divisors, whose sum is σ = 82397952000. Its totient is φ = 4526668800.

The previous prime is 21043543489. The next prime is 21043543531. The reversal of 21043543500 is 534534012.

21043543500 is a `hidden beast` number, since 2 + 104 + 3 + 54 + 3 + 500 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1599951 + ... + 1613049.

It is an arithmetic number, because the mean of its divisors is an integer number (214578000).

Almost surely, 2^21043543500 is an apocalyptic number.

21043543500 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 21043543500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41198976000).

21043543500 is an abundant number, since it is smaller than the sum of its proper divisors (61354408500).

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

21043543500 is a wasteful number, since it uses less digits than its factorization.

21043543500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13151 (or 13133 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 27.

The spelling of 21043543500 in words is "twenty-one billion, forty-three million, five hundred forty-three thousand, five hundred".