21015305216 has 44 divisors (see below), whose sum is σ = 42230428800. Its totient is φ = 10452541440.

The previous prime is 21015305153. The next prime is 21015305231. The reversal of 21015305216 is 61250351012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141860 + ... + 249308.

Almost surely, 2^21015305216 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 21015305216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21115214400).

21015305216 is an abundant number, since it is smaller than the sum of its proper divisors (21215123584).

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

21015305216 is a wasteful number, since it uses less digits than its factorization.

21015305216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107660 (or 107642 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

Adding to 21015305216 its reverse (61250351012), we get a palindrome (82265656228).

The spelling of 21015305216 in words is "twenty-one billion, fifteen million, three hundred five thousand, two hundred sixteen".