3959981521 has 2 divisors, whose sum is σ = 3959981522. Its totient is φ = 3959981520.

The previous prime is 3959981491. The next prime is 3959981561. The reversal of 3959981521 is 1251899593.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3784710400 + 175271121 = 61520^2 + 13239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3959981521 is a prime.

It is a super-2 number, since 2×3959981521² = 31362907293322946882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (3959981561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1979990760 + 1979990761.

It is an arithmetic number, because the mean of its divisors is an integer number (1979990761).

Almost surely, 2^3959981521 is an apocalyptic number.

It is an amenable number.

3959981521 is a deficient number, since it is larger than the sum of its proper divisors (1).

3959981521 is an equidigital number, since it uses as much as digits as its factorization.

3959981521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 874800, while the sum is 52.

The square root of 3959981521 is about 62928.3840647446. The cubic root of 3959981521 is about 1582.0895177904.

The spelling of 3959981521 in words is "three billion, nine hundred fifty-nine million, nine hundred eighty-one thousand, five hundred twenty-one".