6666555661665 has 16 divisors (see below), whose sum is σ = 10954772547648. Its totient is φ = 3459401856576.

The previous prime is 6666555661637. The next prime is 6666555661669. The reversal of 6666555661665 is 5661665556666.

It is not a de Polignac number, because 6666555661665 - 2¹³ = 6666555653473 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 6666555661665.

It is not an unprimeable number, because it can be changed into a prime (6666555661669) 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, 6005905447 + ... + 6005906556.

It is an arithmetic number, because the mean of its divisors is an integer number (684673284228).

Almost surely, 2^{6666555661665} is an apocalyptic number.

It is an amenable number.

6666555661665 is a deficient number, since it is larger than the sum of its proper divisors (4288216885983).

6666555661665 is a wasteful number, since it uses less digits than its factorization.

6666555661665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12011812048.

The product of its digits is 1049760000, while the sum is 69.

The spelling of 6666555661665 in words is "six trillion, six hundred sixty-six billion, five hundred fifty-five million, six hundred sixty-one thousand, six hundred sixty-five".