205749 has 6 divisors (see below), whose sum is σ = 297206. Its totient is φ = 137160.

The previous prime is 205721. The next prime is 205759. The reversal of 205749 is 947502.

205749 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in only one way, i.e., 202500 + 3249 = 450^2 + 57^2 .

It is not a de Polignac number, because 205749 - 2⁸ = 205493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205759) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11422 + ... + 11439.

2²⁰⁵⁷⁴⁹ is an apocalyptic number.

It is an amenable number.

205749 is a deficient number, since it is larger than the sum of its proper divisors (91457).

205749 is a wasteful number, since it uses less digits than its factorization.

205749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22867 (or 22864 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 205749 is about 453.5956348996. The cubic root of 205749 is about 59.0354091766.

The spelling of 205749 in words is "two hundred five thousand, seven hundred forty-nine".