166212809 has 4 divisors (see below), whose sum is σ = 189957504. Its totient is φ = 142468116.

The previous prime is 166212773. The next prime is 166212841. The reversal of 166212809 is 908212661.

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 de Polignac number, because none of the positive numbers 2^k-166212809 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (166212869) 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, 11872337 + ... + 11872350.

It is an arithmetic number, because the mean of its divisors is an integer number (47489376).

Almost surely, 2^166212809 is an apocalyptic number.

It is an amenable number.

166212809 is a deficient number, since it is larger than the sum of its proper divisors (23744695).

166212809 is an equidigital number, since it uses as much as digits as its factorization.

166212809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23744694.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 166212809 is about 12892.3546724406. The cubic root of 166212809 is about 549.8212190274.

The spelling of 166212809 in words is "one hundred sixty-six million, two hundred twelve thousand, eight hundred nine".