638750621 has 2 divisors, whose sum is σ = 638750622. Its totient is φ = 638750620.

The previous prime is 638750611. The next prime is 638750699. The reversal of 638750621 is 126057836.

638750621 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., 548215396 + 90535225 = 23414^2 + 9515^2 .

It is a cyclic number.

It is not a de Polignac number, because 638750621 - 2⁶ = 638750557 is a prime.

It is a super-4 number, since 4×638750621⁴ (a number of 36 digits) contains 4444 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638750611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319375310 + 319375311.

It is an arithmetic number, because the mean of its divisors is an integer number (319375311).

Almost surely, 2^638750621 is an apocalyptic number.

It is an amenable number.

638750621 is a deficient number, since it is larger than the sum of its proper divisors (1).

638750621 is an equidigital number, since it uses as much as digits as its factorization.

638750621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 38.

The square root of 638750621 is about 25273.5161977909. The cubic root of 638750621 is about 861.2127387414.

The spelling of 638750621 in words is "six hundred thirty-eight million, seven hundred fifty thousand, six hundred twenty-one".