165678561 has 8 divisors (see below), whose sum is σ = 245449760. Its totient is φ = 110452356.

The previous prime is 165678553. The next prime is 165678593. The reversal of 165678561 is 165876561.

165678561 is a `hidden beast` number, since 1 + 6 + 567 + 85 + 6 + 1 = 666.

It is not a de Polignac number, because 165678561 - 2³ = 165678553 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (165678551) 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, 3068095 + ... + 3068148.

It is an arithmetic number, because the mean of its divisors is an integer number (30681220).

Almost surely, 2^165678561 is an apocalyptic number.

It is an amenable number.

165678561 is a deficient number, since it is larger than the sum of its proper divisors (79771199).

165678561 is an equidigital number, since it uses as much as digits as its factorization.

165678561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6136252 (or 6136246 counting only the distinct ones).

The product of its digits is 302400, while the sum is 45.

The square root of 165678561 is about 12871.6184297081. The cubic root of 165678561 is about 549.2315008030.

The spelling of 165678561 in words is "one hundred sixty-five million, six hundred seventy-eight thousand, five hundred sixty-one".