664644657 has 4 divisors (see below), whose sum is σ = 886192880. Its totient is φ = 443096436.

The previous prime is 664644641. The next prime is 664644667. The reversal of 664644657 is 756446466.

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 not a de Polignac number, because 664644657 - 2⁴ = 664644641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664644667) 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, 110774107 + ... + 110774112.

It is an arithmetic number, because the mean of its divisors is an integer number (221548220).

Almost surely, 2^664644657 is an apocalyptic number.

It is an amenable number.

664644657 is a deficient number, since it is larger than the sum of its proper divisors (221548223).

664644657 is a wasteful number, since it uses less digits than its factorization.

664644657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221548222.

The product of its digits is 2903040, while the sum is 48.

The square root of 664644657 is about 25780.7031905648. The cubic root of 664644657 is about 872.6963762431.

The spelling of 664644657 in words is "six hundred sixty-four million, six hundred forty-four thousand, six hundred fifty-seven".