991705 has 32 divisors (see below), whose sum is σ = 1491840. Its totient is φ = 622080.

The previous prime is 991703. The next prime is 991717. The reversal of 991705 is 507199.

It is not a de Polignac number, because 991705 - 2¹ = 991703 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991703) 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 31 ways as a sum of consecutive naturals, for example, 13549 + ... + 13621.

It is an arithmetic number, because the mean of its divisors is an integer number (46620).

2⁹⁹¹⁷⁰⁵ is an apocalyptic number.

991705 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

It is an amenable number.

991705 is a deficient number, since it is larger than the sum of its proper divisors (500135).

991705 is a wasteful number, since it uses less digits than its factorization.

991705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121.

The product of its (nonzero) digits is 2835, while the sum is 31.

The square root of 991705 is about 995.8438632637. The cubic root of 991705 is about 99.7227319347.

The spelling of 991705 in words is "nine hundred ninety-one thousand, seven hundred five".