18720699321649 has 32 divisors (see below), whose sum is σ = 20640472123040. Its totient is φ = 16874416668672.

The previous prime is 18720699321619. The next prime is 18720699321659. The reversal of 18720699321649 is 94612399602781.

It can be written as a sum of positive squares in 16 ways, for example, as 37687233424 + 18683012088225 = 194132^2 + 4322385^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18720699321649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18720699321619) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 134093209 + ... + 134232745.

It is an arithmetic number, because the mean of its divisors is an integer number (645014753845).

Almost surely, 2^{18720699321649} is an apocalyptic number.

It is an amenable number.

18720699321649 is a deficient number, since it is larger than the sum of its proper divisors (1919772801391).

18720699321649 is a wasteful number, since it uses less digits than its factorization.

18720699321649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141029.

The product of its (nonzero) digits is 70543872, while the sum is 67.

The spelling of 18720699321649 in words is "eighteen trillion, seven hundred twenty billion, six hundred ninety-nine million, three hundred twenty-one thousand, six hundred forty-nine".