16644696921 has 12 divisors (see below), whose sum is σ = 24380965440. Its totient is φ = 10940175960.

The previous prime is 16644696899. The next prime is 16644696949. The reversal of 16644696921 is 12969644661.

It is not a de Polignac number, because 16644696921 - 2¹¹ = 16644694873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16644696961) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13023381 + ... + 13024658.

It is an arithmetic number, because the mean of its divisors is an integer number (2031747120).

Almost surely, 2^16644696921 is an apocalyptic number.

It is an amenable number.

16644696921 is a deficient number, since it is larger than the sum of its proper divisors (7736268519).

16644696921 is a wasteful number, since it uses less digits than its factorization.

16644696921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26048116 (or 26048113 counting only the distinct ones).

The product of its digits is 3359232, while the sum is 54.

The spelling of 16644696921 in words is "sixteen billion, six hundred forty-four million, six hundred ninety-six thousand, nine hundred twenty-one".