991839 has 8 divisors (see below), whose sum is σ = 1330560. Its totient is φ = 657176.

The previous prime is 991817. The next prime is 991867. The reversal of 991839 is 938199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991839 - 2⁹ = 991327 is a prime.

991839 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 991797 and 991806.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991839.

It is not an unprimeable number, because it can be changed into a prime (991889) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 387 + ... + 1460.

It is an arithmetic number, because the mean of its divisors is an integer number (166320).

2⁹⁹¹⁸³⁹ is an apocalyptic number.

991839 is a deficient number, since it is larger than the sum of its proper divisors (338721).

991839 is a wasteful number, since it uses less digits than its factorization.

991839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2029.

The product of its digits is 17496, while the sum is 39.

The square root of 991839 is about 995.9111406145. The cubic root of 991839 is about 99.7272232718.

It can be divided in two parts, 991 and 839, that added together give a triangular number (1830 = T₆₀).

The spelling of 991839 in words is "nine hundred ninety-one thousand, eight hundred thirty-nine".