638845133 has 2 divisors, whose sum is σ = 638845134. Its totient is φ = 638845132.

The previous prime is 638845121. The next prime is 638845153. The reversal of 638845133 is 331548836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 623650729 + 15194404 = 24973^2 + 3898^2 .

It is a cyclic number.

It is not a de Polignac number, because 638845133 - 2⁶ = 638845069 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638845153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319422566 + 319422567.

It is an arithmetic number, because the mean of its divisors is an integer number (319422567).

Almost surely, 2^638845133 is an apocalyptic number.

It is an amenable number.

638845133 is a deficient number, since it is larger than the sum of its proper divisors (1).

638845133 is an equidigital number, since it uses as much as digits as its factorization.

638845133 is an evil number, because the sum of its binary digits is even.

The product of its digits is 207360, while the sum is 41.

The square root of 638845133 is about 25275.3859119896. The cubic root of 638845133 is about 861.2552127636.

The spelling of 638845133 in words is "six hundred thirty-eight million, eight hundred forty-five thousand, one hundred thirty-three".