205819 has 4 divisors (see below), whose sum is σ = 217944. Its totient is φ = 193696.

The previous prime is 205817. The next prime is 205823. The reversal of 205819 is 918502.

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 205819 - 2¹ = 205817 is a prime.

It is a super-2 number, since 2×205819² = 84722921522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 205793 and 205802.

It is not an unprimeable number, because it can be changed into a prime (205817) 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, 6037 + ... + 6070.

It is an arithmetic number, because the mean of its divisors is an integer number (54486).

2²⁰⁵⁸¹⁹ is an apocalyptic number.

205819 is a deficient number, since it is larger than the sum of its proper divisors (12125).

205819 is a wasteful number, since it uses less digits than its factorization.

205819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12124.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 205819 is about 453.6727895742. The cubic root of 205819 is about 59.0421034337.

It can be divided in two parts, 205 and 819, that added together give a 10-th power (1024 = 2¹⁰).

The spelling of 205819 in words is "two hundred five thousand, eight hundred nineteen".