991759 has 4 divisors (see below), whose sum is σ = 993816. Its totient is φ = 989704.

The previous prime is 991751. The next prime is 991777. The reversal of 991759 is 957199.

991759 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 957199 = 127 ⋅7537.

It is a cyclic number.

It is not a de Polignac number, because 991759 - 2³ = 991751 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 132 + ... + 1414.

It is an arithmetic number, because the mean of its divisors is an integer number (248454).

2⁹⁹¹⁷⁵⁹ is an apocalyptic number.

991759 is a deficient number, since it is larger than the sum of its proper divisors (2057).

991759 is a wasteful number, since it uses less digits than its factorization.

991759 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2056.

The product of its digits is 25515, while the sum is 40.

The square root of 991759 is about 995.8709755787. The cubic root of 991759 is about 99.7245419252.

The spelling of 991759 in words is "nine hundred ninety-one thousand, seven hundred fifty-nine".