3978863521 has 4 divisors (see below), whose sum is σ = 3979711044. Its totient is φ = 3978016000.

The previous prime is 3978863513. The next prime is 3978863533. The reversal of 3978863521 is 1253688793.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1469955600 + 2508907921 = 38340^2 + 50089^2 .

It is a cyclic number.

It is not a de Polignac number, because 3978863521 - 2³ = 3978863513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3978863591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 416680 + ... + 426121.

It is an arithmetic number, because the mean of its divisors is an integer number (994927761).

Almost surely, 2^3978863521 is an apocalyptic number.

It is an amenable number.

3978863521 is a deficient number, since it is larger than the sum of its proper divisors (847523).

3978863521 is an equidigital number, since it uses as much as digits as its factorization.

3978863521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 847522.

The product of its digits is 2177280, while the sum is 52.

The square root of 3978863521 is about 63078.2333376578. The cubic root of 3978863521 is about 1584.6001069000.

The spelling of 3978863521 in words is "three billion, nine hundred seventy-eight million, eight hundred sixty-three thousand, five hundred twenty-one".