16644121 has 4 divisors (see below), whose sum is σ = 17924452. Its totient is φ = 15363792.

The previous prime is 16644119. The next prime is 16644137. The reversal of 16644121 is 12144661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12144661 = 1871 ⋅6491.

It can be written as a sum of positive squares in 2 ways, for example, as 11055625 + 5588496 = 3325^2 + 2364^2 .

It is a cyclic number.

It is not a de Polignac number, because 16644121 - 2¹ = 16644119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16644151) 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, 640146 + ... + 640171.

It is an arithmetic number, because the mean of its divisors is an integer number (4481113).

Almost surely, 2^16644121 is an apocalyptic number.

It is an amenable number.

16644121 is a deficient number, since it is larger than the sum of its proper divisors (1280331).

16644121 is a wasteful number, since it uses less digits than its factorization.

16644121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280330.

The product of its digits is 1152, while the sum is 25.

The square root of 16644121 is about 4079.7207012245. The cubic root of 16644121 is about 255.3212457759.

Adding to 16644121 its reverse (12144661), we get a palindrome (28788782).

The spelling of 16644121 in words is "sixteen million, six hundred forty-four thousand, one hundred twenty-one".