21543202044 has 384 divisors, whose sum is σ = 71779276800. Its totient is φ = 5434490880.

The previous prime is 21543202007. The next prime is 21543202069. The reversal of 21543202044 is 44020234512.

21543202044 is a `hidden beast` number, since 21 + 5 + 432 + 0 + 204 + 4 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 21543201999 and 21543202017.

It is a congruent number.

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, 37336284 + ... + 37336860.

It is an arithmetic number, because the mean of its divisors is an integer number (186925200).

Almost surely, 2^21543202044 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21543202044, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35889638400).

21543202044 is an abundant number, since it is smaller than the sum of its proper divisors (50236074756).

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

21543202044 is a wasteful number, since it uses less digits than its factorization.

21543202044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 770 (or 762 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

Adding to 21543202044 its reverse (44020234512), we get a palindrome (65563436556).

The spelling of 21543202044 in words is "twenty-one billion, five hundred forty-three million, two hundred two thousand, forty-four".