990121211 has 2 divisors, whose sum is σ = 990121212. Its totient is φ = 990121210.

The previous prime is 990121207. The next prime is 990121247. The reversal of 990121211 is 112121099.

990121211 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is an emirp because it is prime and its reverse (112121099) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 990121211 - 2² = 990121207 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (990121201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495060605 + 495060606.

It is an arithmetic number, because the mean of its divisors is an integer number (495060606).

Almost surely, 2^990121211 is an apocalyptic number.

990121211 is a deficient number, since it is larger than the sum of its proper divisors (1).

990121211 is an equidigital number, since it uses as much as digits as its factorization.

990121211 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 26.

The square root of 990121211 is about 31466.1915553821. The cubic root of 990121211 is about 996.6961670419.

The spelling of 990121211 in words is "nine hundred ninety million, one hundred twenty-one thousand, two hundred eleven".