991143239 has 2 divisors, whose sum is σ = 991143240. Its totient is φ = 991143238.

The previous prime is 991143229. The next prime is 991143287. The reversal of 991143239 is 932341199.

It is a weak prime.

It is an emirp because it is prime and its reverse (932341199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991143239 is a prime.

It is a super-2 number, since 2×991143239² = 1964729840430822242, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 991143196 and 991143205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991143229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495571619 + 495571620.

It is an arithmetic number, because the mean of its divisors is an integer number (495571620).

Almost surely, 2^991143239 is an apocalyptic number.

991143239 is a deficient number, since it is larger than the sum of its proper divisors (1).

991143239 is an equidigital number, since it uses as much as digits as its factorization.

991143239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52488, while the sum is 41.

The square root of 991143239 is about 31482.4274635867. The cubic root of 991143239 is about 997.0389873913.

The spelling of 991143239 in words is "nine hundred ninety-one million, one hundred forty-three thousand, two hundred thirty-nine".