204909223561 has 9 divisors (see below), whose sum is σ = 238367476749. Its totient is φ = 175633761324.

The previous prime is 204909223559. The next prime is 204909223573. The reversal of 204909223561 is 165322909402.

The square root of 204909223561 is 452669.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 204909223561 - 2¹ = 204909223559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (204909223501) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3136350 + ... + 3201016.

Almost surely, 2^204909223561 is an apocalyptic number.

204909223561 is the 452669-th square number.

204909223561 is the 226335-th centered octagonal number.

It is an amenable number.

204909223561 is a deficient number, since it is larger than the sum of its proper divisors (33458253188).

204909223561 is an frugal number, since it uses more digits than its factorization.

204909223561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129348 (or 64674 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 43.

The spelling of 204909223561 in words is "two hundred four billion, nine hundred nine million, two hundred twenty-three thousand, five hundred sixty-one".