21906538016 has 96 divisors (see below), whose sum is σ = 47636709120. Its totient is φ = 9833728000.

The previous prime is 21906538013. The next prime is 21906538037. The reversal of 21906538016 is 61083560912.

It is not an unprimeable number, because it can be changed into a prime (21906538013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25561460 + ... + 25562316.

It is an arithmetic number, because the mean of its divisors is an integer number (496215720).

Almost surely, 2^21906538016 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 21906538016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23818354560).

21906538016 is an abundant number, since it is smaller than the sum of its proper divisors (25730171104).

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

21906538016 is a wasteful number, since it uses less digits than its factorization.

21906538016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1698 (or 1690 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 41.

The spelling of 21906538016 in words is "twenty-one billion, nine hundred six million, five hundred thirty-eight thousand, sixteen".