21534411872 has 48 divisors (see below), whose sum is σ = 43365611520. Its totient is φ = 10521641088.

The previous prime is 21534411851. The next prime is 21534411893. The reversal of 21534411872 is 27811443512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21534411851) and next prime (21534411893).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 980273 + ... + 1001999.

It is an arithmetic number, because the mean of its divisors is an integer number (903450240).

Almost surely, 2^21534411872 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 21534411872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21682805760).

21534411872 is an abundant number, since it is smaller than the sum of its proper divisors (21831199648).

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

21534411872 is a wasteful number, since it uses less digits than its factorization.

21534411872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22443 (or 22435 counting only the distinct ones).

The product of its digits is 53760, while the sum is 38.

The spelling of 21534411872 in words is "twenty-one billion, five hundred thirty-four million, four hundred eleven thousand, eight hundred seventy-two".