1666685165 has 16 divisors (see below), whose sum is σ = 2055694512. Its totient is φ = 1296290304.

The previous prime is 1666685161. The next prime is 1666685171. The reversal of 1666685165 is 5615866661.

It can be written as a sum of positive squares in 8 ways, for example, as 15319396 + 1651365769 = 3914^2 + 40637^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666685165 - 2² = 1666685161 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666685161) 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, 303827 + ... + 309263.

It is an arithmetic number, because the mean of its divisors is an integer number (128480907).

Almost surely, 2^1666685165 is an apocalyptic number.

It is an amenable number.

1666685165 is a deficient number, since it is larger than the sum of its proper divisors (389009347).

1666685165 is a wasteful number, since it uses less digits than its factorization.

1666685165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7136.

The product of its digits is 1555200, while the sum is 50.

The square root of 1666685165 is about 40825.0556031465. The cubic root of 1666685165 is about 1185.6354879203.

The spelling of 1666685165 in words is "one billion, six hundred sixty-six million, six hundred eighty-five thousand, one hundred sixty-five".