16651321 has 4 divisors (see below), whose sum is σ = 16675200. Its totient is φ = 16627444.

The previous prime is 16651303. The next prime is 16651331. The reversal of 16651321 is 12315661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16651321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16651331) 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 3 ways as a sum of consecutive naturals, for example, 10861 + ... + 12298.

It is an arithmetic number, because the mean of its divisors is an integer number (4168800).

Almost surely, 2^16651321 is an apocalyptic number.

It is an amenable number.

16651321 is a deficient number, since it is larger than the sum of its proper divisors (23879).

16651321 is an equidigital number, since it uses as much as digits as its factorization.

16651321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23878.

The product of its digits is 1080, while the sum is 25.

The square root of 16651321 is about 4080.6030191627. The cubic root of 16651321 is about 255.3580565304.

Adding to 16651321 its reverse (12315661), we get a palindrome (28966982).

The spelling of 16651321 in words is "sixteen million, six hundred fifty-one thousand, three hundred twenty-one".