664321638 has 8 divisors (see below), whose sum is σ = 1328643288. Its totient is φ = 221440544.

The previous prime is 664321607. The next prime is 664321639. The reversal of 664321638 is 836123466.

It is a sphenic number, since it is the product of 3 distinct primes.

664321638 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 664321596 and 664321605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664321639) 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, 55360131 + ... + 55360142.

It is an arithmetic number, because the mean of its divisors is an integer number (166080411).

Almost surely, 2^664321638 is an apocalyptic number.

664321638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

664321638 is a wasteful number, since it uses less digits than its factorization.

664321638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110720278.

The product of its digits is 124416, while the sum is 39.

The square root of 664321638 is about 25774.4376854278. The cubic root of 664321638 is about 872.5549757780.

The spelling of 664321638 in words is "six hundred sixty-four million, three hundred twenty-one thousand, six hundred thirty-eight".