991745 has 4 divisors (see below), whose sum is σ = 1190100. Its totient is φ = 793392.

The previous prime is 991741. The next prime is 991751. The reversal of 991745 is 547199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 547199 = 173 ⋅3163.

It can be written as a sum of positive squares in 2 ways, for example, as 760384 + 231361 = 872^2 + 481^2 .

It is a cyclic number.

It is not a de Polignac number, because 991745 - 2² = 991741 is a prime.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991745.

It is not an unprimeable number, because it can be changed into a prime (991741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99170 + ... + 99179.

It is an arithmetic number, because the mean of its divisors is an integer number (297525).

2⁹⁹¹⁷⁴⁵ is an apocalyptic number.

It is an amenable number.

991745 is a deficient number, since it is larger than the sum of its proper divisors (198355).

991745 is a wasteful number, since it uses less digits than its factorization.

991745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198354.

The product of its digits is 11340, while the sum is 35.

The square root of 991745 is about 995.8639465309. The cubic root of 991745 is about 99.7240726747.

The spelling of 991745 in words is "nine hundred ninety-one thousand, seven hundred forty-five".