664621691 has 8 divisors (see below), whose sum is σ = 699862800. Its totient is φ = 629406720.

The previous prime is 664621687. The next prime is 664621697. The reversal of 664621691 is 196126466.

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 664621691 - 2² = 664621687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664621697) 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, 66971 + ... + 76251.

It is an arithmetic number, because the mean of its divisors is an integer number (87482850).

Almost surely, 2^664621691 is an apocalyptic number.

664621691 is a deficient number, since it is larger than the sum of its proper divisors (35241109).

664621691 is a wasteful number, since it uses less digits than its factorization.

664621691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13069.

The product of its digits is 93312, while the sum is 41.

The square root of 664621691 is about 25780.2577760580. The cubic root of 664621691 is about 872.6863244680.

The spelling of 664621691 in words is "six hundred sixty-four million, six hundred twenty-one thousand, six hundred ninety-one".