991606211 has 2 divisors, whose sum is σ = 991606212. Its totient is φ = 991606210.

The previous prime is 991606171. The next prime is 991606237. The reversal of 991606211 is 112606199.

It is a strong prime.

It is an emirp because it is prime and its reverse (112606199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991606211 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (991606241) 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, 495803105 + 495803106.

It is an arithmetic number, because the mean of its divisors is an integer number (495803106).

Almost surely, 2^991606211 is an apocalyptic number.

991606211 is a deficient number, since it is larger than the sum of its proper divisors (1).

991606211 is an equidigital number, since it uses as much as digits as its factorization.

991606211 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 35.

The square root of 991606211 is about 31489.7794689007. The cubic root of 991606211 is about 997.1942052118.

The spelling of 991606211 in words is "nine hundred ninety-one million, six hundred six thousand, two hundred eleven".