638865433 has 2 divisors, whose sum is σ = 638865434. Its totient is φ = 638865432.

The previous prime is 638865419. The next prime is 638865449. The reversal of 638865433 is 334568836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 623600784 + 15264649 = 24972^2 + 3907^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638865433 is a prime.

It is not a weakly prime, because it can be changed into another prime (638865473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319432716 + 319432717.

It is an arithmetic number, because the mean of its divisors is an integer number (319432717).

Almost surely, 2^638865433 is an apocalyptic number.

It is an amenable number.

638865433 is a deficient number, since it is larger than the sum of its proper divisors (1).

638865433 is an equidigital number, since it uses as much as digits as its factorization.

638865433 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 46.

The square root of 638865433 is about 25275.7874852595. The cubic root of 638865433 is about 861.2643351078.

The spelling of 638865433 in words is "six hundred thirty-eight million, eight hundred sixty-five thousand, four hundred thirty-three".