9879991 has 4 divisors (see below), whose sum is σ = 10778184. Its totient is φ = 8981800.

The previous prime is 9879983. The next prime is 9879997. The reversal of 9879991 is 1999789.

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 9879991 - 2³ = 9879983 is a prime.

It is a super-2 number, since 2×9879991² = 195228444320162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9879997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 449080 + ... + 449101.

It is an arithmetic number, because the mean of its divisors is an integer number (2694546).

Almost surely, 2^9879991 is an apocalyptic number.

9879991 is a deficient number, since it is larger than the sum of its proper divisors (898193).

9879991 is a wasteful number, since it uses less digits than its factorization.

9879991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 898192.

The product of its digits is 367416, while the sum is 52.

The square root of 9879991 is about 3143.2452974593. The cubic root of 9879991 is about 214.5781597102.

It can be divided in two parts, 98 and 79991, that added together give a square (80089 = 283²).

The spelling of 9879991 in words is "nine million, eight hundred seventy-nine thousand, nine hundred ninety-one".