204420021 has 16 divisors (see below), whose sum is σ = 306289536. Its totient is φ = 120326976.

The previous prime is 204420011. The next prime is 204420037. The reversal of 204420021 is 120024402.

It is not a de Polignac number, because 204420021 - 2¹⁰ = 204418997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204420001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 113050 + ... + 114843.

It is an arithmetic number, because the mean of its divisors is an integer number (19143096).

Almost surely, 2^204420021 is an apocalyptic number.

It is an amenable number.

204420021 is a deficient number, since it is larger than the sum of its proper divisors (101869515).

204420021 is a wasteful number, since it uses less digits than its factorization.

204420021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227932.

The product of its (nonzero) digits is 128, while the sum is 15.

The square root of 204420021 is about 14297.5529724495. The cubic root of 204420021 is about 589.0802686247.

Adding to 204420021 its reverse (120024402), we get a palindrome (324444423).

The spelling of 204420021 in words is "two hundred four million, four hundred twenty thousand, twenty-one".