990989 has 2 divisors, whose sum is σ = 990990. Its totient is φ = 990988.

The previous prime is 990973. The next prime is 991009. The reversal of 990989 is 989099.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 697225 + 293764 = 835^2 + 542^2 .

It is an emirp because it is prime and its reverse (989099) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 990989 - 2⁴ = 990973 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (990289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495494 + 495495.

It is an arithmetic number, because the mean of its divisors is an integer number (495495).

2⁹⁹⁰⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

990989 is a deficient number, since it is larger than the sum of its proper divisors (1).

990989 is an equidigital number, since it uses as much as digits as its factorization.

990989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52488, while the sum is 44.

The square root of 990989 is about 995.4843042459. The cubic root of 990989 is about 99.6987265882.

The spelling of 990989 in words is "nine hundred ninety thousand, nine hundred eighty-nine".