165550561 has 8 divisors (see below), whose sum is σ = 182355264. Its totient is φ = 149038320.

The previous prime is 165550549. The next prime is 165550603. The reversal of 165550561 is 165055561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 165550561 - 2⁷ = 165550433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165556561) 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, 71926 + ... + 74191.

It is an arithmetic number, because the mean of its divisors is an integer number (22794408).

Almost surely, 2^165550561 is an apocalyptic number.

165550561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165550561 is a deficient number, since it is larger than the sum of its proper divisors (16804703).

165550561 is a wasteful number, since it uses less digits than its factorization.

165550561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146231.

The product of its (nonzero) digits is 22500, while the sum is 34.

The square root of 165550561 is about 12866.6452892741. The cubic root of 165550561 is about 549.0900225413.

The spelling of 165550561 in words is "one hundred sixty-five million, five hundred fifty thousand, five hundred sixty-one".