991895 has 16 divisors (see below), whose sum is σ = 1283040. Its totient is φ = 733824.

The previous prime is 991889. The next prime is 991901. The reversal of 991895 is 598199.

It is an interprime number because it is at equal distance from previous prime (991889) and next prime (991901).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991895 is a prime.

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 991895.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 4937 + ... + 5133.

It is an arithmetic number, because the mean of its divisors is an integer number (80190).

2⁹⁹¹⁸⁹⁵ is an apocalyptic number.

991895 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

991895 is a deficient number, since it is larger than the sum of its proper divisors (291145).

991895 is a wasteful number, since it uses less digits than its factorization.

991895 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274.

The product of its digits is 29160, while the sum is 41.

The square root of 991895 is about 995.9392551757. The cubic root of 991895 is about 99.7291001286.

Adding to 991895 its sum of digits (41), we get a triangular number (991936 = T₁₄₀₈).

The spelling of 991895 in words is "nine hundred ninety-one thousand, eight hundred ninety-five".