205006821 has 4 divisors (see below), whose sum is σ = 273342432. Its totient is φ = 136671212.

The previous prime is 205006793. The next prime is 205006853. The reversal of 205006821 is 128600502.

205006821 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 cyclic number.

It is not a de Polignac number, because 205006821 - 2⁷ = 205006693 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 205006791 and 205006800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205006861) 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, 34167801 + ... + 34167806.

It is an arithmetic number, because the mean of its divisors is an integer number (68335608).

Almost surely, 2^205006821 is an apocalyptic number.

It is an amenable number.

205006821 is a deficient number, since it is larger than the sum of its proper divisors (68335611).

205006821 is an equidigital number, since it uses as much as digits as its factorization.

205006821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68335610.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 205006821 is about 14318.0592609473. The cubic root of 205006821 is about 589.6433936204.

The spelling of 205006821 in words is "two hundred five million, six thousand, eight hundred twenty-one".