205990 has 8 divisors (see below), whose sum is σ = 370800. Its totient is φ = 82392.

The previous prime is 205981. The next prime is 205991. The reversal of 205990 is 99502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205991) by changing a digit.

205990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10290 + ... + 10309.

It is an arithmetic number, because the mean of its divisors is an integer number (46350).

2²⁰⁵⁹⁹⁰ is an apocalyptic number.

205990 is a deficient number, since it is larger than the sum of its proper divisors (164810).

205990 is a wasteful number, since it uses less digits than its factorization.

205990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20606.

The product of its (nonzero) digits is 810, while the sum is 25.

The square root of 205990 is about 453.8612122665. The cubic root of 205990 is about 59.0584501670.

The spelling of 205990 in words is "two hundred five thousand, nine hundred ninety".