1666686717 has 12 divisors (see below), whose sum is σ = 2413895484. Its totient is φ = 1108143360.

The previous prime is 1666686701. The next prime is 1666686739. The reversal of 1666686717 is 7176866661.

It can be written as a sum of positive squares in 2 ways, for example, as 1231588836 + 435097881 = 35094^2 + 20859^2 .

It is not a de Polignac number, because 1666686717 - 2⁴ = 1666686701 is a prime.

It is a super-2 number, since 2×1666686717² = 5555689225248476178, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666685717) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 244884 + ... + 251597.

It is an arithmetic number, because the mean of its divisors is an integer number (201157957).

Almost surely, 2^1666686717 is an apocalyptic number.

It is an amenable number.

1666686717 is a deficient number, since it is larger than the sum of its proper divisors (747208767).

1666686717 is a wasteful number, since it uses less digits than its factorization.

1666686717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 496860 (or 496857 counting only the distinct ones).

The product of its digits is 3048192, while the sum is 54.

The square root of 1666686717 is about 40825.0746110770. The cubic root of 1666686717 is about 1185.6358559374.

The spelling of 1666686717 in words is "one billion, six hundred sixty-six million, six hundred eighty-six thousand, seven hundred seventeen".