205987 has 4 divisors (see below), whose sum is σ = 213120. Its totient is φ = 198856.

The previous prime is 205981. The next prime is 205991. The reversal of 205987 is 789502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 205987 - 2¹⁵ = 173219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205981) 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, 3523 + ... + 3580.

It is an arithmetic number, because the mean of its divisors is an integer number (53280).

2²⁰⁵⁹⁸⁷ is an apocalyptic number.

205987 is a deficient number, since it is larger than the sum of its proper divisors (7133).

205987 is an equidigital number, since it uses as much as digits as its factorization.

205987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7132.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 205987 is about 453.8579072794. The cubic root of 205987 is about 59.0581634601.

The spelling of 205987 in words is "two hundred five thousand, nine hundred eighty-seven".