204520031021 has 4 divisors (see below), whose sum is σ = 215284243200. Its totient is φ = 193755818844.

The previous prime is 204520030843. The next prime is 204520031047. The reversal of 204520031021 is 120130025402.

204520031021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 de Polignac number, because none of the positive numbers 2^k-204520031021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 204520030984 and 204520031002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204520033021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5382106061 + ... + 5382106098.

It is an arithmetic number, because the mean of its divisors is an integer number (53821060800).

Almost surely, 2^204520031021 is an apocalyptic number.

It is an amenable number.

204520031021 is a deficient number, since it is larger than the sum of its proper divisors (10764212179).

204520031021 is a wasteful number, since it uses less digits than its factorization.

204520031021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10764212178.

The product of its (nonzero) digits is 480, while the sum is 20.

Adding to 204520031021 its reverse (120130025402), we get a palindrome (324650056423).

The spelling of 204520031021 in words is "two hundred four billion, five hundred twenty million, thirty-one thousand, twenty-one".