204140021 has 4 divisors (see below), whose sum is σ = 204253344. Its totient is φ = 204026700.

The previous prime is 204140017. The next prime is 204140023. The reversal of 204140021 is 120041402.

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 a cyclic number.

It is not a de Polignac number, because 204140021 - 2² = 204140017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 204139978 and 204140005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204140023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53915 + ... + 57576.

It is an arithmetic number, because the mean of its divisors is an integer number (51063336).

Almost surely, 2^204140021 is an apocalyptic number.

It is an amenable number.

204140021 is a deficient number, since it is larger than the sum of its proper divisors (113323).

204140021 is a wasteful number, since it uses less digits than its factorization.

204140021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113322.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 204140021 is about 14287.7577317086. The cubic root of 204140021 is about 588.8111856510.

Adding to 204140021 its reverse (120041402), we get a palindrome (324181423).

The spelling of 204140021 in words is "two hundred four million, one hundred forty thousand, twenty-one".