16201221 has 8 divisors (see below), whose sum is σ = 22872384. Its totient is φ = 10165440.

The previous prime is 16201219. The next prime is 16201247. The reversal of 16201221 is 12210261.

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

It is not a de Polignac number, because 16201221 - 2¹ = 16201219 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 16201221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16201201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 158785 + ... + 158886.

It is an arithmetic number, because the mean of its divisors is an integer number (2859048).

Almost surely, 2^16201221 is an apocalyptic number.

It is an amenable number.

16201221 is a deficient number, since it is larger than the sum of its proper divisors (6671163).

16201221 is a wasteful number, since it uses less digits than its factorization.

16201221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317691.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 16201221 is about 4025.0740365862. The cubic root of 16201221 is about 253.0361564141.

Adding to 16201221 its reverse (12210261), we get a palindrome (28411482).

The spelling of 16201221 in words is "sixteen million, two hundred one thousand, two hundred twenty-one".