66221569 has 2 divisors, whose sum is σ = 66221570. Its totient is φ = 66221568.

The previous prime is 66221567. The next prime is 66221621. The reversal of 66221569 is 96512266.

66221569 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51667344 + 14554225 = 7188^2 + 3815^2 .

It is a cyclic number.

It is not a de Polignac number, because 66221569 - 2¹ = 66221567 is a prime.

It is a super-2 number, since 2×66221569² = 8770592401643522, which contains 22 as substring.

Together with 66221567, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (66221567) 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 as a sum of consecutive naturals, namely, 33110784 + 33110785.

It is an arithmetic number, because the mean of its divisors is an integer number (33110785).

Almost surely, 2^66221569 is an apocalyptic number.

It is an amenable number.

66221569 is a deficient number, since it is larger than the sum of its proper divisors (1).

66221569 is an equidigital number, since it uses as much as digits as its factorization.

66221569 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 37.

The square root of 66221569 is about 8137.6636081863. The cubic root of 66221569 is about 404.5757259892.

The spelling of 66221569 in words is "sixty-six million, two hundred twenty-one thousand, five hundred sixty-nine".