3978795661 has 2 divisors, whose sum is σ = 3978795662. Its totient is φ = 3978795660.

The previous prime is 3978795589. The next prime is 3978795671. The reversal of 3978795661 is 1665978793.

3978795661 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3975302500 + 3493161 = 63050^2 + 1869^2 .

It is an emirp because it is prime and its reverse (1665978793) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3978795661 - 2¹¹ = 3978793613 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 3978795661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3978795671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1989397830 + 1989397831.

It is an arithmetic number, because the mean of its divisors is an integer number (1989397831).

Almost surely, 2^3978795661 is an apocalyptic number.

It is an amenable number.

3978795661 is a deficient number, since it is larger than the sum of its proper divisors (1).

3978795661 is an equidigital number, since it uses as much as digits as its factorization.

3978795661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17146080, while the sum is 61.

The square root of 3978795661 is about 63077.6954319037. The cubic root of 3978795661 is about 1584.5910983331.

The spelling of 3978795661 in words is "three billion, nine hundred seventy-eight million, seven hundred ninety-five thousand, six hundred sixty-one".