9921138828 has 24 divisors (see below), whose sum is σ = 23150989680. Its totient is φ = 3306808320.

The previous prime is 9921138811. The next prime is 9921138841. The reversal of 9921138828 is 8288311299.

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, 246868 + ... + 284228.

It is an arithmetic number, because the mean of its divisors is an integer number (964624570).

Almost surely, 2^9921138828 is an apocalyptic number.

It is an amenable number.

9921138828 is an abundant number, since it is smaller than the sum of its proper divisors (13229850852).

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

9921138828 is a wasteful number, since it uses less digits than its factorization.

9921138828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59497 (or 59495 counting only the distinct ones).

The product of its digits is 497664, while the sum is 51.

The square root of 9921138828 is about 99604.9136739749. The cubic root of 9921138828 is about 2148.7563622952.

The spelling of 9921138828 in words is "nine billion, nine hundred twenty-one million, one hundred thirty-eight thousand, eight hundred twenty-eight".