16653221 has 16 divisors (see below), whose sum is σ = 18735360. Its totient is φ = 14696640.

The previous prime is 16653211. The next prime is 16653227. The reversal of 16653221 is 12235661.

It is a cyclic number.

It is not a de Polignac number, because 16653221 - 2⁶ = 16653157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16653227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 61316 + ... + 61586.

It is an arithmetic number, because the mean of its divisors is an integer number (1170960).

Almost surely, 2^16653221 is an apocalyptic number.

It is an amenable number.

16653221 is a deficient number, since it is larger than the sum of its proper divisors (2082139).

16653221 is a wasteful number, since it uses less digits than its factorization.

16653221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 476.

The product of its digits is 2160, while the sum is 26.

The square root of 16653221 is about 4080.8358212503. The cubic root of 16653221 is about 255.3677687099.

Adding to 16653221 its reverse (12235661), we get a palindrome (28888882).

The spelling of 16653221 in words is "sixteen million, six hundred fifty-three thousand, two hundred twenty-one".