204021561 has 8 divisors (see below), whose sum is σ = 272809600. Its totient is φ = 135623952.

The previous prime is 204021551. The next prime is 204021581. The reversal of 204021561 is 165120402.

204021561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 204021561 - 2⁹ = 204021049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (204021511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96385 + ... + 98478.

It is an arithmetic number, because the mean of its divisors is an integer number (34101200).

Almost surely, 2^204021561 is an apocalyptic number.

It is an amenable number.

204021561 is a deficient number, since it is larger than the sum of its proper divisors (68788039).

204021561 is a wasteful number, since it uses less digits than its factorization.

204021561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195215.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 204021561 is about 14283.6116231155. The cubic root of 204021561 is about 588.6972702628.

Adding to 204021561 its reverse (165120402), we get a palindrome (369141963).

The spelling of 204021561 in words is "two hundred four million, twenty-one thousand, five hundred sixty-one".