66222221 has 16 divisors (see below), whose sum is σ = 74807040. Its totient is φ = 58164480.

The previous prime is 66222209. The next prime is 66222227. The reversal of 66222221 is 12222266.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66222221 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Curzon number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66222227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71600 + ... + 72518.

It is an arithmetic number, because the mean of its divisors is an integer number (4675440).

Almost surely, 2^66222221 is an apocalyptic number.

It is an amenable number.

66222221 is a deficient number, since it is larger than the sum of its proper divisors (8584819).

66222221 is a wasteful number, since it uses less digits than its factorization.

66222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1196.

The product of its digits is 1152, while the sum is 23.

The square root of 66222221 is about 8137.7036687262. The cubic root of 66222221 is about 404.5770537666.

Adding to 66222221 its reverse (12222266), we get a palindrome (78444487).

The spelling of 66222221 in words is "sixty-six million, two hundred twenty-two thousand, two hundred twenty-one".