166216409 has 4 divisors (see below), whose sum is σ = 166244304. Its totient is φ = 166188516.

The previous prime is 166216367. The next prime is 166216411. The reversal of 166216409 is 904612661.

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 166216409 - 2²⁰ = 165167833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166216439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1007 + ... + 18260.

It is an arithmetic number, because the mean of its divisors is an integer number (41561076).

Almost surely, 2^166216409 is an apocalyptic number.

It is an amenable number.

166216409 is a deficient number, since it is larger than the sum of its proper divisors (27895).

166216409 is an equidigital number, since it uses as much as digits as its factorization.

166216409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27894.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 166216409 is about 12892.4942893142. The cubic root of 166216409 is about 549.8251885211.

The spelling of 166216409 in words is "one hundred sixty-six million, two hundred sixteen thousand, four hundred nine".