9991439 has 2 divisors, whose sum is σ = 9991440.
Its totient is φ = 9991438.
The previous prime is 9991433. The next prime is 9991441. The reversal of 9991439 is 9341999.
9991439 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a strong prime.
It is an emirp because it is prime and its reverse (9341999) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 9991439 - 28 = 9991183 is a prime.
Together with 9991441, it forms a pair of twin primes.
It is a Chen prime.
It is a self number, because there is not a number n which added to its sum of digits gives 9991439.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (9991433) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995719 + 4995720.
It is an arithmetic number, because the mean of its divisors is an integer number (4995720).
Almost surely, 29991439 is an apocalyptic number.
9991439 is a deficient number, since it is larger than the sum of its proper divisors (1).
9991439 is an equidigital number, since it uses as much as digits as its factorization.
9991439 is an evil number, because the sum of its binary digits is even.
The product of its digits is 78732, while the sum is 44.
The square root of 9991439 is about 3160.9237573849.
The cubic root of 9991439 is about 215.3819710658.
The spelling of 9991439 in words is "nine million, nine hundred ninety-one thousand, four hundred thirty-nine".