16691694289209 has 9 divisors (see below), whose sum is σ = 24110242788463. Its totient is φ = 11127788021712.

The previous prime is 16691694289159. The next prime is 16691694289223. The reversal of 16691694289209 is 90298249619661.

The square root of 16691694289209 is 4085547.

It is a perfect power (a square), and thus also a powerful number.

16691694289209 is a `hidden beast` number, since 16 + 6 + 9 + 169 + 428 + 9 + 20 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16465765186809 + 225929102400 = 4057803^2 + 475320^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 16691694289209 - 2¹⁵ = 16691694256441 is a prime.

It is a super-2 number, since 2×16691694289209² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16691694285209) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 11575717 + ... + 12937565.

Almost surely, 2^{16691694289209} is an apocalyptic number.

16691694289209 is the 4085547-th square number.

16691694289209 is the 2042774-th centered octagonal number.

It is an amenable number.

16691694289209 is a deficient number, since it is larger than the sum of its proper divisors (7418548499254).

16691694289209 is an frugal number, since it uses more digits than its factorization.

16691694289209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2723704 (or 1361852 counting only the distinct ones).

The product of its (nonzero) digits is 181398528, while the sum is 72.

The spelling of 16691694289209 in words is "sixteen trillion, six hundred ninety-one billion, six hundred ninety-four million, two hundred eighty-nine thousand, two hundred nine".