206810221 has 4 divisors (see below), whose sum is σ = 207073792. Its totient is φ = 206546652.

The previous prime is 206810179. The next prime is 206810237. The reversal of 206810221 is 122018602.

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 a de Polignac number, because none of the positive numbers 2^k-206810221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 206810192 and 206810201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206810921) 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, 130605 + ... + 132178.

It is an arithmetic number, because the mean of its divisors is an integer number (51768448).

Almost surely, 2^206810221 is an apocalyptic number.

It is an amenable number.

206810221 is a deficient number, since it is larger than the sum of its proper divisors (263571).

206810221 is an equidigital number, since it uses as much as digits as its factorization.

206810221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263570.

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 206810221 is about 14380.8977814321. The cubic root of 206810221 is about 591.3673362413.

Adding to 206810221 its reverse (122018602), we get a palindrome (328828823).

The spelling of 206810221 in words is "two hundred six million, eight hundred ten thousand, two hundred twenty-one".