638426863 has 2 divisors, whose sum is σ = 638426864. Its totient is φ = 638426862.

The previous prime is 638426837. The next prime is 638426881. The reversal of 638426863 is 368624836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638426863 - 2²¹ = 636329711 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638426813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319213431 + 319213432.

It is an arithmetic number, because the mean of its divisors is an integer number (319213432).

Almost surely, 2^638426863 is an apocalyptic number.

638426863 is a deficient number, since it is larger than the sum of its proper divisors (1).

638426863 is an equidigital number, since it uses as much as digits as its factorization.

638426863 is an evil number, because the sum of its binary digits is even.

The product of its digits is 995328, while the sum is 46.

The square root of 638426863 is about 25267.1103017341. The cubic root of 638426863 is about 861.0672090013.

The spelling of 638426863 in words is "six hundred thirty-eight million, four hundred twenty-six thousand, eight hundred sixty-three".