991161443 has 2 divisors, whose sum is σ = 991161444. Its totient is φ = 991161442.

The previous prime is 991161403. The next prime is 991161503. The reversal of 991161443 is 344161199.

It is a weak prime.

It is an emirp because it is prime and its reverse (344161199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991161443 - 2¹⁴ = 991145059 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991161397 and 991161406.

It is not a weakly prime, because it can be changed into another prime (991161403) 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, 495580721 + 495580722.

It is an arithmetic number, because the mean of its divisors is an integer number (495580722).

Almost surely, 2^991161443 is an apocalyptic number.

991161443 is a deficient number, since it is larger than the sum of its proper divisors (1).

991161443 is an equidigital number, since it uses as much as digits as its factorization.

991161443 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 38.

The square root of 991161443 is about 31482.7165759246. The cubic root of 991161443 is about 997.0450914490.

The spelling of 991161443 in words is "nine hundred ninety-one million, one hundred sixty-one thousand, four hundred forty-three".