16644355021 has 16 divisors (see below), whose sum is σ = 19556728576. Its totient is φ = 13866443136.

The previous prime is 16644355009. The next prime is 16644355031. The reversal of 16644355021 is 12055344661.

16644355021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-16644355021 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16644355031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 217225 + ... + 283681.

It is an arithmetic number, because the mean of its divisors is an integer number (1222295536).

Almost surely, 2^16644355021 is an apocalyptic number.

It is an amenable number.

16644355021 is a deficient number, since it is larger than the sum of its proper divisors (2912373555).

16644355021 is an equidigital number, since it uses as much as digits as its factorization.

16644355021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67468.

The product of its (nonzero) digits is 86400, while the sum is 37.

Adding to 16644355021 its reverse (12055344661), we get a palindrome (28699699682).

The spelling of 16644355021 in words is "sixteen billion, six hundred forty-four million, three hundred fifty-five thousand, twenty-one".