66221689 has 2 divisors, whose sum is σ = 66221690. Its totient is φ = 66221688.

The previous prime is 66221657. The next prime is 66221699. The reversal of 66221689 is 98612266.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65205625 + 1016064 = 8075^2 + 1008^2 .

It is a cyclic number.

It is not a de Polignac number, because 66221689 - 2⁵ = 66221657 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66221699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33110844 + 33110845.

It is an arithmetic number, because the mean of its divisors is an integer number (33110845).

Almost surely, 2^66221689 is an apocalyptic number.

It is an amenable number.

66221689 is a deficient number, since it is larger than the sum of its proper divisors (1).

66221689 is an equidigital number, since it uses as much as digits as its factorization.

66221689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 40.

The square root of 66221689 is about 8137.6709813066. The cubic root of 66221689 is about 404.5759703660.

The spelling of 66221689 in words is "sixty-six million, two hundred twenty-one thousand, six hundred eighty-nine".