990209 has 4 divisors (see below), whose sum is σ = 1080240. Its totient is φ = 900180.

The previous prime is 990181. The next prime is 990211. The reversal of 990209 is 902099.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 902099 = 11 ⋅82009.

It is a cyclic number.

It is not a de Polignac number, because 990209 - 2¹² = 986113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (990239) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44999 + ... + 45020.

It is an arithmetic number, because the mean of its divisors is an integer number (270060).

It is a Proth number, since it is equal to 967 ⋅ 2¹⁰ + 1 and 967 < 2¹⁰.

2⁹⁹⁰²⁰⁹ is an apocalyptic number.

It is an amenable number.

990209 is a deficient number, since it is larger than the sum of its proper divisors (90031).

990209 is a wasteful number, since it uses less digits than its factorization.

990209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90030.

The product of its (nonzero) digits is 1458, while the sum is 29.

The square root of 990209 is about 995.0924580158. The cubic root of 990209 is about 99.6725623494.

The spelling of 990209 in words is "nine hundred ninety thousand, two hundred nine".