1666666681985 has 16 divisors (see below), whose sum is σ = 2001463439040. Its totient is φ = 1332358077120.

The previous prime is 1666666681913. The next prime is 1666666681993. The reversal of 1666666681985 is 5891866666661.

It is a de Polignac number, because none of the positive numbers 2^k-1666666681985 is a prime.

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, 45297326 + ... + 45334104.

It is an arithmetic number, because the mean of its divisors is an integer number (125091464940).

Almost surely, 2^{1666666681985} is an apocalyptic number.

It is an amenable number.

1666666681985 is a deficient number, since it is larger than the sum of its proper divisors (334796757055).

1666666681985 is a wasteful number, since it uses less digits than its factorization.

1666666681985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43168.

The product of its digits is 806215680, while the sum is 74.

The spelling of 1666666681985 in words is "one trillion, six hundred sixty-six billion, six hundred sixty-six million, six hundred eighty-one thousand, nine hundred eighty-five".