666002221 has 4 divisors (see below), whose sum is σ = 667100032. Its totient is φ = 664904412.

The previous prime is 666002203. The next prime is 666002263. The reversal of 666002221 is 122200666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 666002221 - 2⁷ = 666002093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666002521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 547995 + ... + 549208.

It is an arithmetic number, because the mean of its divisors is an integer number (166775008).

Almost surely, 2^666002221 is an apocalyptic number.

It is an amenable number.

666002221 is a deficient number, since it is larger than the sum of its proper divisors (1097811).

666002221 is a wasteful number, since it uses less digits than its factorization.

666002221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1097810.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 666002221 is about 25807.0188320929. The cubic root of 666002221 is about 873.2901448869.

Adding to 666002221 its reverse (122200666), we get a palindrome (788202887).

The spelling of 666002221 in words is "six hundred sixty-six million, two thousand, two hundred twenty-one".