991447 has 2 divisors, whose sum is σ = 991448. Its totient is φ = 991446.

The previous prime is 991429. The next prime is 991453. The reversal of 991447 is 744199.

It is a strong prime.

It is an emirp because it is prime and its reverse (744199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991447 - 2¹⁵ = 958679 is a prime.

991447 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991427) 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, 495723 + 495724.

It is an arithmetic number, because the mean of its divisors is an integer number (495724).

2⁹⁹¹⁴⁴⁷ is an apocalyptic number.

991447 is a deficient number, since it is larger than the sum of its proper divisors (1).

991447 is an equidigital number, since it uses as much as digits as its factorization.

991447 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 34.

The square root of 991447 is about 995.7143164583. The cubic root of 991447 is about 99.7140832955.

The spelling of 991447 in words is "nine hundred ninety-one thousand, four hundred forty-seven".