3871784821 has 4 divisors (see below), whose sum is σ = 3976427692. Its totient is φ = 3767141952.

The previous prime is 3871784783. The next prime is 3871784843. The reversal of 3871784821 is 1284871783.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1284871783 = 13 ⋅98836291.

It can be written as a sum of positive squares in 2 ways, for example, as 3670542225 + 201242596 = 60585^2 + 14186^2 .

It is a cyclic number.

It is not a de Polignac number, because 3871784821 - 2⁹ = 3871784309 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 (3871784321) 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, 52321380 + ... + 52321453.

It is an arithmetic number, because the mean of its divisors is an integer number (994106923).

Almost surely, 2^3871784821 is an apocalyptic number.

It is an amenable number.

3871784821 is a deficient number, since it is larger than the sum of its proper divisors (104642871).

3871784821 is a wasteful number, since it uses less digits than its factorization.

3871784821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104642870.

The product of its digits is 602112, while the sum is 49.

The square root of 3871784821 is about 62223.6676916429. The cubic root of 3871784821 is about 1570.2557930420.

The spelling of 3871784821 in words is "three billion, eight hundred seventy-one million, seven hundred eighty-four thousand, eight hundred twenty-one".