1666939670665 has 16 divisors (see below), whose sum is σ = 2210080629888. Its totient is φ = 1200537623296.

The previous prime is 1666939670639. The next prime is 1666939670677. The reversal of 1666939670665 is 5660769396661.

It is a cyclic number.

It is not a de Polignac number, because 1666939670665 - 2¹¹ = 1666939668617 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1666939670594 and 1666939670603.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 426325327 + ... + 426329236.

It is an arithmetic number, because the mean of its divisors is an integer number (138130039368).

Almost surely, 2^{1666939670665} is an apocalyptic number.

It is an amenable number.

1666939670665 is a deficient number, since it is larger than the sum of its proper divisors (543140959223).

1666939670665 is a wasteful number, since it uses less digits than its factorization.

1666939670665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 852654608.

The product of its (nonzero) digits is 396809280, while the sum is 70.

The spelling of 1666939670665 in words is "one trillion, six hundred sixty-six billion, nine hundred thirty-nine million, six hundred seventy thousand, six hundred sixty-five".