16661568683405 has 8 divisors (see below), whose sum is σ = 19993904347032. Its totient is φ = 13329240328768.

The previous prime is 16661568683371. The next prime is 16661568683423. The reversal of 16661568683405 is 50438686516661.

It can be written as a sum of positive squares in 4 ways, for example, as 1045011418564 + 15616557264841 = 1022258^2 + 3951779^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16661568683405 - 2⁶ = 16661568683341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7778819 + ... + 9686751.

It is an arithmetic number, because the mean of its divisors is an integer number (2499238043379).

Almost surely, 2^{16661568683405} is an apocalyptic number.

It is an amenable number.

16661568683405 is a deficient number, since it is larger than the sum of its proper divisors (3332335663627).

16661568683405 is a wasteful number, since it uses less digits than its factorization.

16661568683405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3654495.

The product of its (nonzero) digits is 149299200, while the sum is 65.

The spelling of 16661568683405 in words is "sixteen trillion, six hundred sixty-one billion, five hundred sixty-eight million, six hundred eighty-three thousand, four hundred five".