664456221 has 24 divisors (see below), whose sum is σ = 1127564256. Its totient is φ = 371723040.

The previous prime is 664456217. The next prime is 664456307. The reversal of 664456221 is 122654466.

664456221 is a `hidden beast` number, since 6 + 644 + 5 + 6 + 2 + 2 + 1 = 666.

It is not a de Polignac number, because 664456221 - 2² = 664456217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664456421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 256855 + ... + 259428.

It is an arithmetic number, because the mean of its divisors is an integer number (46981844).

Almost surely, 2^664456221 is an apocalyptic number.

It is an amenable number.

664456221 is a deficient number, since it is larger than the sum of its proper divisors (463108035).

664456221 is a wasteful number, since it uses less digits than its factorization.

664456221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516313 (or 516310 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 664456221 is about 25777.0483376200. The cubic root of 664456221 is about 872.6138945961.

The spelling of 664456221 in words is "six hundred sixty-four million, four hundred fifty-six thousand, two hundred twenty-one".