217221 has 8 divisors (see below), whose sum is σ = 294624. Its totient is φ = 142320.

The previous prime is 217219. The next prime is 217223. The reversal of 217221 is 122712.

217221 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (217219) and next prime (217223).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 217221 - 2¹ = 217219 is a prime.

217221 is strictly pandigital in base 7.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 217221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 411 + ... + 776.

It is an arithmetic number, because the mean of its divisors is an integer number (36828).

2²¹⁷²²¹ is an apocalyptic number.

It is an amenable number.

217221 is a deficient number, since it is larger than the sum of its proper divisors (77403).

217221 is a wasteful number, since it uses less digits than its factorization.

217221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1251.

The product of its digits is 56, while the sum is 15.

The square root of 217221 is about 466.0697372712. The cubic root of 217221 is about 60.1128431961.

Adding to 217221 its reverse (122712), we get a palindrome (339933).

The spelling of 217221 in words is "two hundred seventeen thousand, two hundred twenty-one", and thus it is an iban number.