665606221 has 8 divisors (see below), whose sum is σ = 762511680. Its totient is φ = 569155488.

The previous prime is 665606213. The next prime is 665606237. The reversal of 665606221 is 122606566.

665606221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 665606221 - 2³ = 665606213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665606251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110536 + ... + 116401.

It is an arithmetic number, because the mean of its divisors is an integer number (95313960).

Almost surely, 2^665606221 is an apocalyptic number.

It is an amenable number.

665606221 is a deficient number, since it is larger than the sum of its proper divisors (96905459).

665606221 is a wasteful number, since it uses less digits than its factorization.

665606221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227363.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 665606221 is about 25799.3453599118. The cubic root of 665606221 is about 873.1170266147.

The spelling of 665606221 in words is "six hundred sixty-five million, six hundred six thousand, two hundred twenty-one".