204645 has 16 divisors (see below), whose sum is σ = 374400. Its totient is φ = 93504.

The previous prime is 204641. The next prime is 204667. The reversal of 204645 is 546402.

204645 = 98² + 99² + ... + 115².

It is a happy number.

It is not a de Polignac number, because 204645 - 2² = 204641 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a d-powerful number, because it can be written as 2¹⁷ + 0 + 6⁵ + 4⁴ + 4⁸ + 5 .

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 870 + ... + 1079.

It is an arithmetic number, because the mean of its divisors is an integer number (23400).

2²⁰⁴⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

204645 is a deficient number, since it is larger than the sum of its proper divisors (169755).

204645 is a wasteful number, since it uses less digits than its factorization.

204645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1964.

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 204645 is about 452.3770551211. The cubic root of 204645 is about 58.9296297855.

The spelling of 204645 in words is "two hundred four thousand, six hundred forty-five".