210210221 has 4 divisors (see below), whose sum is σ = 226380252. Its totient is φ = 194040192.

The previous prime is 210210193. The next prime is 210210223. The reversal of 210210221 is 122012012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 37576900 + 172633321 = 6130^2 + 13139^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-210210221 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210210223) 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, 8084996 + ... + 8085021.

It is an arithmetic number, because the mean of its divisors is an integer number (56595063).

Almost surely, 2^210210221 is an apocalyptic number.

It is an amenable number.

210210221 is a deficient number, since it is larger than the sum of its proper divisors (16170031).

210210221 is a wasteful number, since it uses less digits than its factorization.

210210221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16170030.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 210210221 is about 14498.6282454583. The cubic root of 210210221 is about 594.5904683712.

Adding to 210210221 its reverse (122012012), we get a palindrome (332222233).

The spelling of 210210221 in words is "two hundred ten million, two hundred ten thousand, two hundred twenty-one".