21543405444 has 144 divisors (see below), whose sum is σ = 61133776704. Its totient is φ = 6341088000.

The previous prime is 21543405419. The next prime is 21543405461. The reversal of 21543405444 is 44450434512.

21543405444 is a `hidden beast` number, since 21 + 54 + 3 + 40 + 544 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21543405399 and 21543405408.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2114707 + ... + 2124869.

It is an arithmetic number, because the mean of its divisors is an integer number (424540116).

Almost surely, 2^21543405444 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 21543405444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30566888352).

21543405444 is an abundant number, since it is smaller than the sum of its proper divisors (39590371260).

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

21543405444 is a wasteful number, since it uses less digits than its factorization.

21543405444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10338 (or 10333 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 36.

Adding to 21543405444 its reverse (44450434512), we get a palindrome (65993839956).

The spelling of 21543405444 in words is "twenty-one billion, five hundred forty-three million, four hundred five thousand, four hundred forty-four".