66221291 has 2 divisors, whose sum is σ = 66221292. Its totient is φ = 66221290.

The previous prime is 66221263. The next prime is 66221317. The reversal of 66221291 is 19212266.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66221291 - 2⁶ = 66221227 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66221891) 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, 33110645 + 33110646.

It is an arithmetic number, because the mean of its divisors is an integer number (33110646).

Almost surely, 2^66221291 is an apocalyptic number.

66221291 is a deficient number, since it is larger than the sum of its proper divisors (1).

66221291 is an equidigital number, since it uses as much as digits as its factorization.

66221291 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 29.

The square root of 66221291 is about 8137.6465270986. The cubic root of 66221291 is about 404.5751598483.

The spelling of 66221291 in words is "sixty-six million, two hundred twenty-one thousand, two hundred ninety-one".