9921688056 has 192 divisors, whose sum is σ = 32103751680. Its totient is φ = 2811957120.

The previous prime is 9921688013. The next prime is 9921688057. The reversal of 9921688056 is 6508861299.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 9921687993 and 9921688011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9921688057) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1725346 + ... + 1731086.

It is an arithmetic number, because the mean of its divisors is an integer number (167207040).

Almost surely, 2^9921688056 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 9921688056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16051875840).

9921688056 is an abundant number, since it is smaller than the sum of its proper divisors (22182063624).

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

9921688056 is a wasteful number, since it uses less digits than its factorization.

9921688056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5896 (or 5880 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 54.

The square root of 9921688056 is about 99607.6706684781. The cubic root of 9921688056 is about 2148.7960128301.

The spelling of 9921688056 in words is "nine billion, nine hundred twenty-one million, six hundred eighty-eight thousand, fifty-six".