16659221 has 2 divisors, whose sum is σ = 16659222. Its totient is φ = 16659220.

The previous prime is 16659217. The next prime is 16659229. The reversal of 16659221 is 12295661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16080100 + 579121 = 4010^2 + 761^2 .

It is a cyclic number.

It is not a de Polignac number, because 16659221 - 2² = 16659217 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16659229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8329610 + 8329611.

It is an arithmetic number, because the mean of its divisors is an integer number (8329611).

Almost surely, 2^16659221 is an apocalyptic number.

It is an amenable number.

16659221 is a deficient number, since it is larger than the sum of its proper divisors (1).

16659221 is an equidigital number, since it uses as much as digits as its factorization.

16659221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 32.

The square root of 16659221 is about 4081.5708985634. The cubic root of 16659221 is about 255.3984339014.

The spelling of 16659221 in words is "sixteen million, six hundred fifty-nine thousand, two hundred twenty-one".