16409221 has 4 divisors (see below), whose sum is σ = 16519500. Its totient is φ = 16298944.

The previous prime is 16409213. The next prime is 16409227. The reversal of 16409221 is 12290461.

16409221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3556996 + 12852225 = 1886^2 + 3585^2 .

It is a cyclic number.

It is not a de Polignac number, because 16409221 - 2³ = 16409213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16409227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54916 + ... + 55213.

It is an arithmetic number, because the mean of its divisors is an integer number (4129875).

Almost surely, 2^16409221 is an apocalyptic number.

It is an amenable number.

16409221 is a deficient number, since it is larger than the sum of its proper divisors (110279).

16409221 is a wasteful number, since it uses less digits than its factorization.

16409221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110278.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 16409221 is about 4050.8296681050. The cubic root of 16409221 is about 254.1144265056.

Adding to 16409221 its reverse (12290461), we get a palindrome (28699682).

The spelling of 16409221 in words is "sixteen million, four hundred nine thousand, two hundred twenty-one".