15661665859 has 16 divisors (see below), whose sum is σ = 17954377920. Its totient is φ = 13382853120.

The previous prime is 15661665787. The next prime is 15661665889. The reversal of 15661665859 is 95856616651.

It is not a de Polignac number, because 15661665859 - 2⁹ = 15661665347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15661665889) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3984207 + ... + 3988135.

It is an arithmetic number, because the mean of its divisors is an integer number (1122148620).

Almost surely, 2^15661665859 is an apocalyptic number.

15661665859 is a deficient number, since it is larger than the sum of its proper divisors (2292712061).

15661665859 is a wasteful number, since it uses less digits than its factorization.

15661665859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5550.

The product of its digits is 11664000, while the sum is 58.

The spelling of 15661665859 in words is "fifteen billion, six hundred sixty-one million, six hundred sixty-five thousand, eight hundred fifty-nine".