201990 has 16 divisors (see below), whose sum is σ = 484848. Its totient is φ = 53856.

The previous prime is 201979. The next prime is 201997. The reversal of 201990 is 99102.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201997) by changing a digit.

201990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3337 + ... + 3396.

It is an arithmetic number, because the mean of its divisors is an integer number (30303).

2²⁰¹⁹⁹⁰ is an apocalyptic number.

201990 is an abundant number, since it is smaller than the sum of its proper divisors (282858).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

201990 is a wasteful number, since it uses less digits than its factorization.

201990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6743.

The product of its (nonzero) digits is 162, while the sum is 21.

The square root of 201990 is about 449.4329760932. The cubic root of 201990 is about 58.6736748400.

The spelling of 201990 in words is "two hundred one thousand, nine hundred ninety".