205011021 has 4 divisors (see below), whose sum is σ = 273348032. Its totient is φ = 136674012.

The previous prime is 205011019. The next prime is 205011031. The reversal of 205011021 is 120110502.

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 not a de Polignac number, because 205011021 - 2¹ = 205011019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 205010988 and 205011006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205011031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34168501 + ... + 34168506.

It is an arithmetic number, because the mean of its divisors is an integer number (68337008).

Almost surely, 2^205011021 is an apocalyptic number.

It is an amenable number.

205011021 is a deficient number, since it is larger than the sum of its proper divisors (68337011).

205011021 is an equidigital number, since it uses as much as digits as its factorization.

205011021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68337010.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 205011021 is about 14318.2059281182. The cubic root of 205011021 is about 589.6474202919.

Adding to 205011021 its reverse (120110502), we get a palindrome (325121523).

The spelling of 205011021 in words is "two hundred five million, eleven thousand, twenty-one".