165666565 has 16 divisors (see below), whose sum is σ = 203055408. Its totient is φ = 129724416.

The previous prime is 165666551. The next prime is 165666577. The reversal of 165666565 is 565666561.

It can be written as a sum of positive squares in 8 ways, for example, as 10962721 + 154703844 = 3311^2 + 12438^2 .

It is a cyclic number.

It is not a de Polignac number, because 165666565 - 2⁷ = 165666437 is a prime.

It is a super-3 number, since 3×165666565³ (a number of 26 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

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, 48349 + ... + 51661.

It is an arithmetic number, because the mean of its divisors is an integer number (12690963).

Almost surely, 2^165666565 is an apocalyptic number.

It is an amenable number.

165666565 is a deficient number, since it is larger than the sum of its proper divisors (37388843).

165666565 is a wasteful number, since it uses less digits than its factorization.

165666565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3528.

The product of its digits is 972000, while the sum is 46.

The square root of 165666565 is about 12871.1524348055. The cubic root of 165666565 is about 549.2182447324.

The spelling of 165666565 in words is "one hundred sixty-five million, six hundred sixty-six thousand, five hundred sixty-five".