991034921 has 2 divisors, whose sum is σ = 991034922. Its totient is φ = 991034920.

The previous prime is 991034917. The next prime is 991034923. The reversal of 991034921 is 129430199.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 990990400 + 44521 = 31480^2 + 211^2 .

It is a cyclic number.

It is not a de Polignac number, because 991034921 - 2² = 991034917 is a prime.

Together with 991034923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (991034923) 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, 495517460 + 495517461.

It is an arithmetic number, because the mean of its divisors is an integer number (495517461).

Almost surely, 2^991034921 is an apocalyptic number.

It is an amenable number.

991034921 is a deficient number, since it is larger than the sum of its proper divisors (1).

991034921 is an equidigital number, since it uses as much as digits as its factorization.

991034921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 991034921 is about 31480.7071235701. The cubic root of 991034921 is about 997.0026652940.

The spelling of 991034921 in words is "nine hundred ninety-one million, thirty-four thousand, nine hundred twenty-one".