991693 has 2 divisors, whose sum is σ = 991694. Its totient is φ = 991692.

The previous prime is 991663. The next prime is 991703. The reversal of 991693 is 396199.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 887364 + 104329 = 942^2 + 323^2 .

It is an emirp because it is prime and its reverse (396199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991693 - 2⁹ = 991181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991603) 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 as a sum of consecutive naturals, namely, 495846 + 495847.

It is an arithmetic number, because the mean of its divisors is an integer number (495847).

2⁹⁹¹⁶⁹³ is an apocalyptic number.

It is an amenable number.

991693 is a deficient number, since it is larger than the sum of its proper divisors (1).

991693 is an equidigital number, since it uses as much as digits as its factorization.

991693 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13122, while the sum is 37.

The square root of 991693 is about 995.8378382046. The cubic root of 991693 is about 99.7223297057.

The spelling of 991693 in words is "nine hundred ninety-one thousand, six hundred ninety-three".