991757 has 4 divisors (see below), whose sum is σ = 1068060. Its totient is φ = 915456.

The previous prime is 991751. The next prime is 991777. The reversal of 991757 is 757199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 757199 = 137 ⋅5527.

It can be written as a sum of positive squares in 2 ways, for example, as 106276 + 885481 = 326^2 + 941^2 .

It is a cyclic number.

It is not a de Polignac number, because 991757 - 2⁴ = 991741 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 991757.

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 991757.

It is not an unprimeable number, because it can be changed into a prime (991751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38132 + ... + 38157.

It is an arithmetic number, because the mean of its divisors is an integer number (267015).

2⁹⁹¹⁷⁵⁷ is an apocalyptic number.

It is an amenable number.

991757 is a deficient number, since it is larger than the sum of its proper divisors (76303).

991757 is a wasteful number, since it uses less digits than its factorization.

991757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76302.

The product of its digits is 19845, while the sum is 38.

The square root of 991757 is about 995.8699714320. The cubic root of 991757 is about 99.7244748897.

The spelling of 991757 in words is "nine hundred ninety-one thousand, seven hundred fifty-seven".