16541221 has 8 divisors (see below), whose sum is σ = 17549784. Its totient is φ = 15536640.

The previous prime is 16541219. The next prime is 16541251. The reversal of 16541221 is 12214561.

It can be written as a sum of positive squares in 4 ways, for example, as 4368100 + 12173121 = 2090^2 + 3489^2 .

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

It is not a de Polignac number, because 16541221 - 2¹ = 16541219 is a prime.

It is a super-2 number, since 2×16541221² = 547223984341682, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16541192 and 16541201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16541201) 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, 15691 + ... + 16711.

It is an arithmetic number, because the mean of its divisors is an integer number (2193723).

Almost surely, 2^16541221 is an apocalyptic number.

It is an amenable number.

16541221 is a deficient number, since it is larger than the sum of its proper divisors (1008563).

16541221 is a wasteful number, since it uses less digits than its factorization.

16541221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1991.

The product of its digits is 480, while the sum is 22.

The square root of 16541221 is about 4067.0899916279. The cubic root of 16541221 is about 254.7939948408.

Adding to 16541221 its reverse (12214561), we get a palindrome (28755782).

The spelling of 16541221 in words is "sixteen million, five hundred forty-one thousand, two hundred twenty-one".