991247239 has 2 divisors, whose sum is σ = 991247240. Its totient is φ = 991247238.

The previous prime is 991247221. The next prime is 991247267. The reversal of 991247239 is 932742199.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (932742199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991247239 - 2²⁹ = 454376327 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991241239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495623619 + 495623620.

It is an arithmetic number, because the mean of its divisors is an integer number (495623620).

Almost surely, 2^991247239 is an apocalyptic number.

991247239 is a deficient number, since it is larger than the sum of its proper divisors (1).

991247239 is an equidigital number, since it uses as much as digits as its factorization.

991247239 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 46.

The square root of 991247239 is about 31484.0791353344. The cubic root of 991247239 is about 997.0738590506.

The spelling of 991247239 in words is "nine hundred ninety-one million, two hundred forty-seven thousand, two hundred thirty-nine".