206310221 has 4 divisors (see below), whose sum is σ = 222180252. Its totient is φ = 190440192.

The previous prime is 206310217. The next prime is 206310233. The reversal of 206310221 is 122013602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122013602 = 2 ⋅61006801.

It can be written as a sum of positive squares in 2 ways, for example, as 88153321 + 118156900 = 9389^2 + 10870^2 .

It is a cyclic number.

It is not a de Polignac number, because 206310221 - 2² = 206310217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 206310221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206310271) 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, 7934996 + ... + 7935021.

It is an arithmetic number, because the mean of its divisors is an integer number (55545063).

Almost surely, 2^206310221 is an apocalyptic number.

It is an amenable number.

206310221 is a deficient number, since it is larger than the sum of its proper divisors (15870031).

206310221 is a wasteful number, since it uses less digits than its factorization.

206310221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15870030.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 206310221 is about 14363.5030894277. The cubic root of 206310221 is about 590.8903735516.

Adding to 206310221 its reverse (122013602), we get a palindrome (328323823).

The spelling of 206310221 in words is "two hundred six million, three hundred ten thousand, two hundred twenty-one".