991830397 has 2 divisors, whose sum is σ = 991830398. Its totient is φ = 991830396.

The previous prime is 991830391. The next prime is 991830517. The reversal of 991830397 is 793038199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 934586041 + 57244356 = 30571^2 + 7566^2 .

It is a cyclic number.

It is not a de Polignac number, because 991830397 - 2¹¹ = 991828349 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 991830397.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991830391) 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, 495915198 + 495915199.

It is an arithmetic number, because the mean of its divisors is an integer number (495915199).

Almost surely, 2^991830397 is an apocalyptic number.

It is an amenable number.

991830397 is a deficient number, since it is larger than the sum of its proper divisors (1).

991830397 is an equidigital number, since it uses as much as digits as its factorization.

991830397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 367416, while the sum is 49.

The square root of 991830397 is about 31493.3389306374. The cubic root of 991830397 is about 997.2693493339.

The spelling of 991830397 in words is "nine hundred ninety-one million, eight hundred thirty thousand, three hundred ninety-seven".