638320031 has 2 divisors, whose sum is σ = 638320032. Its totient is φ = 638320030.

The previous prime is 638319971. The next prime is 638320061. The reversal of 638320031 is 130023836.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638320031 is a prime.

It is a super-2 number, since 2×638320031² = 814904923951681922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638320061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319160015 + 319160016.

It is an arithmetic number, because the mean of its divisors is an integer number (319160016).

Almost surely, 2^638320031 is an apocalyptic number.

638320031 is a deficient number, since it is larger than the sum of its proper divisors (1).

638320031 is an equidigital number, since it uses as much as digits as its factorization.

638320031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 638320031 is about 25264.9961606963. The cubic root of 638320031 is about 861.0191770502.

Adding to 638320031 its reverse (130023836), we get a palindrome (768343867).

The spelling of 638320031 in words is "six hundred thirty-eight million, three hundred twenty thousand, thirty-one".