991847 has 4 divisors (see below), whose sum is σ = 993840. Its totient is φ = 989856.

The previous prime is 991817. The next prime is 991867. The reversal of 991847 is 748199.

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 991847 - 2¹⁴ = 975463 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 991847.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 479 + ... + 1487.

It is an arithmetic number, because the mean of its divisors is an integer number (248460).

2⁹⁹¹⁸⁴⁷ is an apocalyptic number.

991847 is a deficient number, since it is larger than the sum of its proper divisors (1993).

991847 is a wasteful number, since it uses less digits than its factorization.

991847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1992.

The product of its digits is 18144, while the sum is 38.

The square root of 991847 is about 995.9151570290. The cubic root of 991847 is about 99.7274913985.

The spelling of 991847 in words is "nine hundred ninety-one thousand, eight hundred forty-seven".