3938475721 has 2 divisors, whose sum is σ = 3938475722. Its totient is φ = 3938475720.

The previous prime is 3938475713. The next prime is 3938475733. The reversal of 3938475721 is 1275748393.

3938475721 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., 2976793600 + 961682121 = 54560^2 + 31011^2 .

It is an emirp because it is prime and its reverse (1275748393) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3938475721 - 2³ = 3938475713 is a prime.

It is not a weakly prime, because it can be changed into another prime (3938470721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1969237860 + 1969237861.

It is an arithmetic number, because the mean of its divisors is an integer number (1969237861).

Almost surely, 2^3938475721 is an apocalyptic number.

It is an amenable number.

3938475721 is a deficient number, since it is larger than the sum of its proper divisors (1).

3938475721 is an equidigital number, since it uses as much as digits as its factorization.

3938475721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1270080, while the sum is 49.

The square root of 3938475721 is about 62757.2762394927. The cubic root of 3938475721 is about 1579.2203226036.

The spelling of 3938475721 in words is "three billion, nine hundred thirty-eight million, four hundred seventy-five thousand, seven hundred twenty-one".