3947390861 has 2 divisors, whose sum is σ = 3947390862. Its totient is φ = 3947390860.

The previous prime is 3947390807. The next prime is 3947390873. The reversal of 3947390861 is 1680937493.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2394242761 + 1553148100 = 48931^2 + 39410^2 .

It is a cyclic number.

It is not a de Polignac number, because 3947390861 - 2¹⁰ = 3947389837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3947390891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1973695430 + 1973695431.

It is an arithmetic number, because the mean of its divisors is an integer number (1973695431).

Almost surely, 2^3947390861 is an apocalyptic number.

It is an amenable number.

3947390861 is a deficient number, since it is larger than the sum of its proper divisors (1).

3947390861 is an equidigital number, since it uses as much as digits as its factorization.

3947390861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 979776, while the sum is 50.

The square root of 3947390861 is about 62828.2648256340. The cubic root of 3947390861 is about 1580.4109998726.

The spelling of 3947390861 in words is "three billion, nine hundred forty-seven million, three hundred ninety thousand, eight hundred sixty-one".