638765399 has 2 divisors, whose sum is σ = 638765400. Its totient is φ = 638765398.

The previous prime is 638765359. The next prime is 638765401. The reversal of 638765399 is 993567836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638765399 - 2⁸ = 638765143 is a prime.

Together with 638765401, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638765359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319382699 + 319382700.

It is an arithmetic number, because the mean of its divisors is an integer number (319382700).

Almost surely, 2^638765399 is an apocalyptic number.

638765399 is a deficient number, since it is larger than the sum of its proper divisors (1).

638765399 is an equidigital number, since it uses as much as digits as its factorization.

638765399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7348320, while the sum is 56.

The square root of 638765399 is about 25273.8085574770. The cubic root of 638765399 is about 861.2193803024.

The spelling of 638765399 in words is "six hundred thirty-eight million, seven hundred sixty-five thousand, three hundred ninety-nine".