9928991 has 4 divisors (see below), whose sum is σ = 10271400. Its totient is φ = 9586584.

The previous prime is 9928981. The next prime is 9928999. The reversal of 9928991 is 1998299.

9928991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 9928991 - 2⁶ = 9928927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9928999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 171161 + ... + 171218.

It is an arithmetic number, because the mean of its divisors is an integer number (2567850).

Almost surely, 2^9928991 is an apocalyptic number.

9928991 is a deficient number, since it is larger than the sum of its proper divisors (342409).

9928991 is a wasteful number, since it uses less digits than its factorization.

9928991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342408.

The product of its digits is 104976, while the sum is 47.

The square root of 9928991 is about 3151.0301490148. The cubic root of 9928991 is about 214.9323096804.

The spelling of 9928991 in words is "nine million, nine hundred twenty-eight thousand, nine hundred ninety-one".