204570021 has 4 divisors (see below), whose sum is σ = 272760032. Its totient is φ = 136380012.

The previous prime is 204570019. The next prime is 204570059. The reversal of 204570021 is 120075402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 204570021 - 2¹ = 204570019 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 204570021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204570011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34095001 + ... + 34095006.

It is an arithmetic number, because the mean of its divisors is an integer number (68190008).

Almost surely, 2^204570021 is an apocalyptic number.

It is an amenable number.

204570021 is a deficient number, since it is larger than the sum of its proper divisors (68190011).

204570021 is an equidigital number, since it uses as much as digits as its factorization.

204570021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68190010.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 204570021 is about 14302.7976633944. The cubic root of 204570021 is about 589.2243191532.

The spelling of 204570021 in words is "two hundred four million, five hundred seventy thousand, twenty-one".