16660561999 has 2 divisors, whose sum is σ = 16660562000. Its totient is φ = 16660561998.

The previous prime is 16660561961. The next prime is 16660562027. The reversal of 16660561999 is 99916506661.

It is a strong prime.

It is an emirp because it is prime and its reverse (99916506661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16660561999 - 2⁹ = 16660561487 is a prime.

It is a super-2 number, since 2×16660561999² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16660561949) 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 as a sum of consecutive naturals, namely, 8330280999 + 8330281000.

It is an arithmetic number, because the mean of its divisors is an integer number (8330281000).

Almost surely, 2^16660561999 is an apocalyptic number.

16660561999 is a deficient number, since it is larger than the sum of its proper divisors (1).

16660561999 is an equidigital number, since it uses as much as digits as its factorization.

16660561999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4723920, while the sum is 58.

The spelling of 16660561999 in words is "sixteen billion, six hundred sixty million, five hundred sixty-one thousand, nine hundred ninety-nine".