165478309 has 4 divisors (see below), whose sum is σ = 166093740. Its totient is φ = 164862880.

The previous prime is 165478301. The next prime is 165478387. The reversal of 165478309 is 903874561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3629025 + 161849284 = 1905^2 + 12722^2 .

It is a cyclic number.

It is not a de Polignac number, because 165478309 - 2³ = 165478301 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165478301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 307312 + ... + 307849.

It is an arithmetic number, because the mean of its divisors is an integer number (41523435).

Almost surely, 2^165478309 is an apocalyptic number.

It is an amenable number.

165478309 is a deficient number, since it is larger than the sum of its proper divisors (615431).

165478309 is an equidigital number, since it uses as much as digits as its factorization.

165478309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 615430.

The product of its (nonzero) digits is 181440, while the sum is 43.

The square root of 165478309 is about 12863.8372579880. The cubic root of 165478309 is about 549.0101302816.

The spelling of 165478309 in words is "one hundred sixty-five million, four hundred seventy-eight thousand, three hundred nine".