3872805821 has 4 divisors (see below), whose sum is σ = 3897473532. Its totient is φ = 3848138112.

The previous prime is 3872805817. The next prime is 3872805857. The reversal of 3872805821 is 1285082783.

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 2467605625 + 1405200196 = 49675^2 + 37486^2 .

It is a cyclic number.

It is not a de Polignac number, because 3872805821 - 2² = 3872805817 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 (3872804821) 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, 12333620 + ... + 12333933.

It is an arithmetic number, because the mean of its divisors is an integer number (974368383).

Almost surely, 2^3872805821 is an apocalyptic number.

It is an amenable number.

3872805821 is a deficient number, since it is larger than the sum of its proper divisors (24667711).

3872805821 is a wasteful number, since it uses less digits than its factorization.

3872805821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24667710.

The product of its (nonzero) digits is 215040, while the sum is 44.

The square root of 3872805821 is about 62231.8714245362. The cubic root of 3872805821 is about 1570.3938077935.

The spelling of 3872805821 in words is "three billion, eight hundred seventy-two million, eight hundred five thousand, eight hundred twenty-one".