3947855981 has 2 divisors, whose sum is σ = 3947855982. Its totient is φ = 3947855980.

The previous prime is 3947855971. The next prime is 3947856001. The reversal of 3947855981 is 1895587493.

3947855981 is digitally balanced in base 3, 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., 3758793481 + 189062500 = 61309^2 + 13750^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3947855981 is a prime.

It is a super-2 number, since 2×3947855981² = 31171133693434944722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 3947855981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3947855911) 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, 1973927990 + 1973927991.

It is an arithmetic number, because the mean of its divisors is an integer number (1973927991).

Almost surely, 2^3947855981 is an apocalyptic number.

It is an amenable number.

3947855981 is a deficient number, since it is larger than the sum of its proper divisors (1).

3947855981 is an equidigital number, since it uses as much as digits as its factorization.

3947855981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10886400, while the sum is 59.

The square root of 3947855981 is about 62831.9662353487. The cubic root of 3947855981 is about 1580.4730705686.

It can be divided in two parts, 39478 and 55981, that added together give a palindrome (95459).

The spelling of 3947855981 in words is "three billion, nine hundred forty-seven million, eight hundred fifty-five thousand, nine hundred eighty-one".