9888991 has 4 divisors (see below), whose sum is σ = 11301712. Its totient is φ = 8476272.

The previous prime is 9888979. The next prime is 9888997. The reversal of 9888991 is 1998889.

9888991 is digitally balanced in base 3, 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, and also an emirpimes, since its reverse is a distinct semiprime: 1998889 = 83 ⋅24083.

It is not a de Polignac number, because 9888991 - 2⁷ = 9888863 is a prime.

It is a Duffinian number.

9888991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9888997) 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, 706350 + ... + 706363.

It is an arithmetic number, because the mean of its divisors is an integer number (2825428).

Almost surely, 2^9888991 is an apocalyptic number.

9888991 is a deficient number, since it is larger than the sum of its proper divisors (1412721).

9888991 is a wasteful number, since it uses less digits than its factorization.

9888991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1412720.

The product of its digits is 373248, while the sum is 52.

The square root of 9888991 is about 3144.6766129445. The cubic root of 9888991 is about 214.6432953072.

The spelling of 9888991 in words is "nine million, eight hundred eighty-eight thousand, nine hundred ninety-one".