16445221 has 24 divisors (see below), whose sum is σ = 19067136. Its totient is φ = 14152320.

The previous prime is 16445183. The next prime is 16445227. The reversal of 16445221 is 12254461.

It is a happy number.

It is not a de Polignac number, because 16445221 - 2¹⁵ = 16412453 is a prime.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

Its product of digits (1920) is a multiple of the sum of its prime divisors (160).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16445227) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 225241 + ... + 225313.

It is an arithmetic number, because the mean of its divisors is an integer number (794464).

Almost surely, 2^16445221 is an apocalyptic number.

It is an amenable number.

16445221 is a deficient number, since it is larger than the sum of its proper divisors (2621915).

16445221 is a wasteful number, since it uses less digits than its factorization.

16445221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 160 counting only the distinct ones).

The product of its digits is 1920, while the sum is 25.

The square root of 16445221 is about 4055.2707677786. The cubic root of 16445221 is about 254.3001236717.

Adding to 16445221 its reverse (12254461), we get a palindrome (28699682).

The spelling of 16445221 in words is "sixteen million, four hundred forty-five thousand, two hundred twenty-one".