638940773 has 2 divisors, whose sum is σ = 638940774. Its totient is φ = 638940772.

The previous prime is 638940769. The next prime is 638940791. The reversal of 638940773 is 377049836.

It is a happy number.

638940773 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 387971809 + 250968964 = 19697^2 + 15842^2 .

It is a cyclic number.

It is not a de Polignac number, because 638940773 - 2² = 638940769 is a prime.

It is a super-2 number, since 2×638940773² = 816490622803675058, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638940793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319470386 + 319470387.

It is an arithmetic number, because the mean of its divisors is an integer number (319470387).

Almost surely, 2^638940773 is an apocalyptic number.

It is an amenable number.

638940773 is a deficient number, since it is larger than the sum of its proper divisors (1).

638940773 is an equidigital number, since it uses as much as digits as its factorization.

638940773 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 762048, while the sum is 47.

The square root of 638940773 is about 25277.2778004278. The cubic root of 638940773 is about 861.2981894488.

The spelling of 638940773 in words is "six hundred thirty-eight million, nine hundred forty thousand, seven hundred seventy-three".