638563867 has 2 divisors, whose sum is σ = 638563868. Its totient is φ = 638563866.

The previous prime is 638563819. The next prime is 638563879. The reversal of 638563867 is 768365836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638563867 - 2¹⁹ = 638039579 is a prime.

It is not a weakly prime, because it can be changed into another prime (638563817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319281933 + 319281934.

It is an arithmetic number, because the mean of its divisors is an integer number (319281934).

Almost surely, 2^638563867 is an apocalyptic number.

638563867 is a deficient number, since it is larger than the sum of its proper divisors (1).

638563867 is an equidigital number, since it uses as much as digits as its factorization.

638563867 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4354560, while the sum is 52.

The square root of 638563867 is about 25269.8212696489. The cubic root of 638563867 is about 861.1287985224.

The spelling of 638563867 in words is "six hundred thirty-eight million, five hundred sixty-three thousand, eight hundred sixty-seven".