638932321 has 4 divisors (see below), whose sum is σ = 660964500. Its totient is φ = 616900144.

The previous prime is 638932309. The next prime is 638932409. The reversal of 638932321 is 123239836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 395572321 + 243360000 = 19889^2 + 15600^2 .

It is a cyclic number.

It is not a de Polignac number, because 638932321 - 2⁹ = 638931809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638935321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11016046 + ... + 11016103.

It is an arithmetic number, because the mean of its divisors is an integer number (165241125).

Almost surely, 2^638932321 is an apocalyptic number.

It is an amenable number.

638932321 is a deficient number, since it is larger than the sum of its proper divisors (22032179).

638932321 is a wasteful number, since it uses less digits than its factorization.

638932321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22032178.

The product of its digits is 46656, while the sum is 37.

The square root of 638932321 is about 25277.1106141505. The cubic root of 638932321 is about 861.2943916401.

The spelling of 638932321 in words is "six hundred thirty-eight million, nine hundred thirty-two thousand, three hundred twenty-one".