204509813 has 12 divisors (see below), whose sum is σ = 226373868. Its totient is φ = 184103040.

The previous prime is 204509803. The next prime is 204509843. The reversal of 204509813 is 318905402.

It can be written as a sum of positive squares in 2 ways, for example, as 82119844 + 122389969 = 9062^2 + 11063^2 .

It is a de Polignac number, because none of the positive numbers 2^k-204509813 is a prime.

It is a super-2 number, since 2×204509813² = 83648527226589938, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 204509813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204509803) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2378 + ... + 20363.

It is an arithmetic number, because the mean of its divisors is an integer number (18864489).

Almost surely, 2^204509813 is an apocalyptic number.

204509813 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

204509813 is a deficient number, since it is larger than the sum of its proper divisors (21864055).

204509813 is a wasteful number, since it uses less digits than its factorization.

204509813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22804 (or 22781 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 204509813 is about 14300.6927454582. The cubic root of 204509813 is about 589.1665076542.

The spelling of 204509813 in words is "two hundred four million, five hundred nine thousand, eight hundred thirteen".