165516409 has 4 divisors (see below), whose sum is σ = 170855680. Its totient is φ = 160177140.

The previous prime is 165516401. The next prime is 165516419. The reversal of 165516409 is 904615561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 165516409 - 2³ = 165516401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165516401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2669589 + ... + 2669650.

It is an arithmetic number, because the mean of its divisors is an integer number (42713920).

Almost surely, 2^165516409 is an apocalyptic number.

It is an amenable number.

165516409 is a deficient number, since it is larger than the sum of its proper divisors (5339271).

165516409 is an equidigital number, since it uses as much as digits as its factorization.

165516409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5339270.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 165516409 is about 12865.3180683573. The cubic root of 165516409 is about 549.0522620489.

The spelling of 165516409 in words is "one hundred sixty-five million, five hundred sixteen thousand, four hundred nine".