638320807 has 2 divisors, whose sum is σ = 638320808. Its totient is φ = 638320806.

The previous prime is 638320757. The next prime is 638320829. The reversal of 638320807 is 708023836.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638320807 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638320867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319160403 + 319160404.

It is an arithmetic number, because the mean of its divisors is an integer number (319160404).

Almost surely, 2^638320807 is an apocalyptic number.

638320807 is a deficient number, since it is larger than the sum of its proper divisors (1).

638320807 is an equidigital number, since it uses as much as digits as its factorization.

638320807 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 37.

The square root of 638320807 is about 25265.0115179075. The cubic root of 638320807 is about 861.0195259612.

The spelling of 638320807 in words is "six hundred thirty-eight million, three hundred twenty thousand, eight hundred seven".