16530221 has 2 divisors, whose sum is σ = 16530222. Its totient is φ = 16530220.

The previous prime is 16530211. The next prime is 16530251. The reversal of 16530221 is 12203561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12348196 + 4182025 = 3514^2 + 2045^2 .

It is an emirp because it is prime and its reverse (12203561) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16530221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 16530193 and 16530202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16530211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8265110 + 8265111.

It is an arithmetic number, because the mean of its divisors is an integer number (8265111).

Almost surely, 2^16530221 is an apocalyptic number.

It is an amenable number.

16530221 is a deficient number, since it is larger than the sum of its proper divisors (1).

16530221 is an equidigital number, since it uses as much as digits as its factorization.

16530221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 16530221 is about 4065.7374484834. The cubic root of 16530221 is about 254.7375025289.

Adding to 16530221 its reverse (12203561), we get a palindrome (28733782).

The spelling of 16530221 in words is "sixteen million, five hundred thirty thousand, two hundred twenty-one".