664066221 has 32 divisors (see below), whose sum is σ = 1124917248. Its totient is φ = 338973120.

The previous prime is 664066219. The next prime is 664066229. The reversal of 664066221 is 122660466.

It is not a de Polignac number, because 664066221 - 2¹ = 664066219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664066229) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 30771 + ... + 47696.

It is an arithmetic number, because the mean of its divisors is an integer number (35153664).

Almost surely, 2^664066221 is an apocalyptic number.

It is an amenable number.

664066221 is a deficient number, since it is larger than the sum of its proper divisors (460851027).

664066221 is a wasteful number, since it uses less digits than its factorization.

664066221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78521.

The product of its (nonzero) digits is 20736, while the sum is 33.

The square root of 664066221 is about 25769.4823580141. The cubic root of 664066221 is about 872.4431354034.

It can be divided in two parts, 66406 and 6221, that added together give a palindrome (72627).

The spelling of 664066221 in words is "six hundred sixty-four million, sixty-six thousand, two hundred twenty-one".