165556161 has 12 divisors (see below), whose sum is σ = 239406180. Its totient is φ = 110246400.

The previous prime is 165556147. The next prime is 165556163. The reversal of 165556161 is 161655561.

It can be written as a sum of positive squares in 2 ways, for example, as 921600 + 164634561 = 960^2 + 12831^2 .

It is not a de Polignac number, because 165556161 - 2¹¹ = 165554113 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (165556163) 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, 1540 + ... + 18261.

It is an arithmetic number, because the mean of its divisors is an integer number (19950515).

Almost surely, 2^165556161 is an apocalyptic number.

It is an amenable number.

165556161 is a deficient number, since it is larger than the sum of its proper divisors (73850019).

165556161 is a wasteful number, since it uses less digits than its factorization.

165556161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20736 (or 20733 counting only the distinct ones).

The product of its digits is 27000, while the sum is 36.

The square root of 165556161 is about 12866.8629043757. The cubic root of 165556161 is about 549.0962137404.

The spelling of 165556161 in words is "one hundred sixty-five million, five hundred fifty-six thousand, one hundred sixty-one".