664426621 has 4 divisors (see below), whose sum is σ = 664740544. Its totient is φ = 664112700.

The previous prime is 664426619. The next prime is 664426643. The reversal of 664426621 is 126624466.

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 a cyclic number.

It is not a de Polignac number, because 664426621 - 2¹ = 664426619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664426681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 153765 + ... + 158026.

It is an arithmetic number, because the mean of its divisors is an integer number (166185136).

Almost surely, 2^664426621 is an apocalyptic number.

It is an amenable number.

664426621 is a deficient number, since it is larger than the sum of its proper divisors (313923).

664426621 is a wasteful number, since it uses less digits than its factorization.

664426621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313922.

The product of its digits is 82944, while the sum is 37.

The square root of 664426621 is about 25776.4741770476. The cubic root of 664426621 is about 872.6009367548.

The spelling of 664426621 in words is "six hundred sixty-four million, four hundred twenty-six thousand, six hundred twenty-one".