991129 has 2 divisors, whose sum is σ = 991130. Its totient is φ = 991128.

The previous prime is 991127. The next prime is 991147. The reversal of 991129 is 921199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 725904 + 265225 = 852^2 + 515^2 .

It is an emirp because it is prime and its reverse (921199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991129 - 2¹ = 991127 is a prime.

Together with 991127, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 991129.

It is not a weakly prime, because it can be changed into another prime (991127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495564 + 495565.

It is an arithmetic number, because the mean of its divisors is an integer number (495565).

2⁹⁹¹¹²⁹ is an apocalyptic number.

It is an amenable number.

991129 is a deficient number, since it is larger than the sum of its proper divisors (1).

991129 is an equidigital number, since it uses as much as digits as its factorization.

991129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1458, while the sum is 31.

The square root of 991129 is about 995.5546192952. The cubic root of 991129 is about 99.7034212802.

The spelling of 991129 in words is "nine hundred ninety-one thousand, one hundred twenty-nine".