3978557161 has 2 divisors, whose sum is σ = 3978557162. Its totient is φ = 3978557160.

The previous prime is 3978557137. The next prime is 3978557171. The reversal of 3978557161 is 1617558793.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2229728400 + 1748828761 = 47220^2 + 41819^2 .

It is an emirp because it is prime and its reverse (1617558793) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3978557161 - 2¹³ = 3978548969 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 3978557099 and 3978557108.

It is not a weakly prime, because it can be changed into another prime (3978557111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1989278580 + 1989278581.

It is an arithmetic number, because the mean of its divisors is an integer number (1989278581).

Almost surely, 2^3978557161 is an apocalyptic number.

It is an amenable number.

3978557161 is a deficient number, since it is larger than the sum of its proper divisors (1).

3978557161 is an equidigital number, since it uses as much as digits as its factorization.

3978557161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1587600, while the sum is 52.

The square root of 3978557161 is about 63075.8048779403. The cubic root of 3978557161 is about 1584.5594361116.

It can be divided in two parts, 397 and 8557161, that added together give a palindrome (8557558).

The spelling of 3978557161 in words is "three billion, nine hundred seventy-eight million, five hundred fifty-seven thousand, one hundred sixty-one".