20204021 has 4 divisors (see below), whose sum is σ = 20696844. Its totient is φ = 19711200.

The previous prime is 20204017. The next prime is 20204027. The reversal of 20204021 is 12040202.

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 579121 + 19624900 = 761^2 + 4430^2 .

It is a cyclic number.

It is not a de Polignac number, because 20204021 - 2² = 20204017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20203993 and 20204011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20204027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 246350 + ... + 246431.

It is an arithmetic number, because the mean of its divisors is an integer number (5174211).

Almost surely, 2^20204021 is an apocalyptic number.

It is an amenable number.

20204021 is a deficient number, since it is larger than the sum of its proper divisors (492823).

20204021 is an equidigital number, since it uses as much as digits as its factorization.

20204021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492822.

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 20204021 is about 4494.8883189686. Note that the first 3 decimals coincide. The cubic root of 20204021 is about 272.3616378076.

Adding to 20204021 its reverse (12040202), we get a palindrome (32244223).

The spelling of 20204021 in words is "twenty million, two hundred four thousand, twenty-one".