203404021 has 4 divisors (see below), whose sum is σ = 203591212. Its totient is φ = 203216832.

The previous prime is 203404009. The next prime is 203404079. The reversal of 203404021 is 120404302.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 164839921 + 38564100 = 12839^2 + 6210^2 .

It is a cyclic number.

It is not a de Polignac number, because 203404021 - 2⁹ = 203403509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 203403986 and 203404004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (203401021) 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, 91956 + ... + 94141.

It is an arithmetic number, because the mean of its divisors is an integer number (50897803).

Almost surely, 2^203404021 is an apocalyptic number.

It is an amenable number.

203404021 is a deficient number, since it is larger than the sum of its proper divisors (187191).

203404021 is a wasteful number, since it uses less digits than its factorization.

203404021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187190.

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 203404021 is about 14261.9781587268. The cubic root of 203404021 is about 588.1027064255.

Adding to 203404021 its reverse (120404302), we get a palindrome (323808323).

The spelling of 203404021 in words is "two hundred three million, four hundred four thousand, twenty-one".