9921437928 has 160 divisors (see below), whose sum is σ = 28540512000. Its totient is φ = 3218548608.

The previous prime is 9921437923. The next prime is 9921437971. The reversal of 9921437928 is 8297341299.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (9921437923) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 6059926 + ... + 6061562.

It is an arithmetic number, because the mean of its divisors is an integer number (178378200).

Almost surely, 2^9921437928 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 9921437928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14270256000).

9921437928 is an abundant number, since it is smaller than the sum of its proper divisors (18619074072).

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

9921437928 is a wasteful number, since it uses less digits than its factorization.

9921437928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1901 (or 1888 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 54.

The square root of 9921437928 is about 99606.4150946113. The cubic root of 9921437928 is about 2148.7779554672. Note that the first 3 decimals are identical.

The spelling of 9921437928 in words is "nine billion, nine hundred twenty-one million, four hundred thirty-seven thousand, nine hundred twenty-eight".