3944115810821 has 4 divisors (see below), whose sum is σ = 3944146595532. Its totient is φ = 3944085026112.

The previous prime is 3944115810793. The next prime is 3944115810827. The reversal of 3944115810821 is 1280185114493.

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 2628710968900 + 1315404841921 = 1621330^2 + 1146911^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3944115810821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3944115810827) 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, 15199370 + ... + 15456683.

It is an arithmetic number, because the mean of its divisors is an integer number (986036648883).

Almost surely, 2^{3944115810821} is an apocalyptic number.

It is an amenable number.

3944115810821 is a deficient number, since it is larger than the sum of its proper divisors (30784711).

3944115810821 is a wasteful number, since it uses less digits than its factorization.

3944115810821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30784710.

The product of its (nonzero) digits is 276480, while the sum is 47.

The spelling of 3944115810821 in words is "three trillion, nine hundred forty-four billion, one hundred fifteen million, eight hundred ten thousand, eight hundred twenty-one".