9991879 has 2 divisors, whose sum is σ = 9991880.
Its totient is φ = 9991878.
The previous prime is 9991847. The next prime is 9991939. The reversal of 9991879 is 9781999.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 9991879 - 25 = 9991847 is a prime.
It is a super-3 number, since 3×99918793 (a number of 22 digits) contains 333 as substring.
9991879 is a lucky number.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (9991379) 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 as a sum of consecutive naturals, namely, 4995939 + 4995940.
It is an arithmetic number, because the mean of its divisors is an integer number (4995940).
Almost surely, 29991879 is an apocalyptic number.
9991879 is a deficient number, since it is larger than the sum of its proper divisors (1).
9991879 is an equidigital number, since it uses as much as digits as its factorization.
9991879 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 367416, while the sum is 52.
The square root of 9991879 is about 3160.9933565258.
The cubic root of 9991879 is about 215.3851326616.
The spelling of 9991879 in words is "nine million, nine hundred ninety-one thousand, eight hundred seventy-nine".