990181 has 2 divisors, whose sum is σ = 990182. Its totient is φ = 990180.

The previous prime is 990179. The next prime is 990211. The reversal of 990181 is 181099.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 982081 + 8100 = 991^2 + 90^2 .

It is a cyclic number.

It is not a de Polignac number, because 990181 - 2¹ = 990179 is a prime.

It is a super-2 number, since 2×990181² = 1960916825522, which contains 22 as substring.

Together with 990179, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (990151) 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, 495090 + 495091.

It is an arithmetic number, because the mean of its divisors is an integer number (495091).

2⁹⁹⁰¹⁸¹ is an apocalyptic number.

It is an amenable number.

990181 is a deficient number, since it is larger than the sum of its proper divisors (1).

990181 is an equidigital number, since it uses as much as digits as its factorization.

990181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 990181 is about 995.0783888720. The cubic root of 990181 is about 99.6716228649.

The spelling of 990181 in words is "nine hundred ninety thousand, one hundred eighty-one".