638788933 has 2 divisors, whose sum is σ = 638788934. Its totient is φ = 638788932.

The previous prime is 638788907. The next prime is 638788963. The reversal of 638788933 is 339887836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 577056484 + 61732449 = 24022^2 + 7857^2 .

It is a cyclic number.

It is not a de Polignac number, because 638788933 - 2⁵ = 638788901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638788963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319394466 + 319394467.

It is an arithmetic number, because the mean of its divisors is an integer number (319394467).

Almost surely, 2^638788933 is an apocalyptic number.

It is an amenable number.

638788933 is a deficient number, since it is larger than the sum of its proper divisors (1).

638788933 is an equidigital number, since it uses as much as digits as its factorization.

638788933 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5225472, while the sum is 55.

The square root of 638788933 is about 25274.2741339885. The cubic root of 638788933 is about 861.2299567927.

The spelling of 638788933 in words is "six hundred thirty-eight million, seven hundred eighty-eight thousand, nine hundred thirty-three".