66221 has 2 divisors, whose sum is σ = 66222. Its totient is φ = 66220.

The previous prime is 66191. The next prime is 66239. The reversal of 66221 is 12266.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62500 + 3721 = 250^2 + 61^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66221 is a prime.

It is a Chen prime.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 66221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33110 + 33111.

It is an arithmetic number, because the mean of its divisors is an integer number (33111).

2⁶⁶²²¹ is an apocalyptic number.

It is an amenable number.

66221 is a deficient number, since it is larger than the sum of its proper divisors (1).

66221 is an equidigital number, since it uses as much as digits as its factorization.

66221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 144, while the sum is 17.

The square root of 66221 is about 257.3344127784. The cubic root of 66221 is about 40.4574567232.

Adding to 66221 its reverse (12266), we get a palindrome (78487).

The spelling of 66221 in words is "sixty-six thousand, two hundred twenty-one".