1666681985 has 8 divisors (see below), whose sum is σ = 2064535296. Its totient is φ = 1290334320.

The previous prime is 1666681981. The next prime is 1666682041. The reversal of 1666681985 is 5891866661.

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

It is not a de Polignac number, because 1666681985 - 2² = 1666681981 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1666681985.

It is not an unprimeable number, because it can be changed into a prime (1666681981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5376239 + ... + 5376548.

It is an arithmetic number, because the mean of its divisors is an integer number (258066912).

Almost surely, 2^1666681985 is an apocalyptic number.

It is an amenable number.

1666681985 is a deficient number, since it is larger than the sum of its proper divisors (397853311).

1666681985 is a wasteful number, since it uses less digits than its factorization.

1666681985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10752823.

The product of its digits is 3732480, while the sum is 56.

The square root of 1666681985 is about 40825.0166564571. The cubic root of 1666681985 is about 1185.6347338640.

The spelling of 1666681985 in words is "one billion, six hundred sixty-six million, six hundred eighty-one thousand, nine hundred eighty-five".