3805821 has 6 divisors (see below), whose sum is σ = 5497310. Its totient is φ = 2537208.

The previous prime is 3805819. The next prime is 3805829. The reversal of 3805821 is 1285083.

It is a happy number.

3805821 is a `hidden beast` number, since 3 + 80 + 582 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 2924100 + 881721 = 1710^2 + 939^2 .

It is not a de Polignac number, because 3805821 - 2¹ = 3805819 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 (3805829) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 211426 + ... + 211443.

Almost surely, 2^3805821 is an apocalyptic number.

It is an amenable number.

3805821 is a deficient number, since it is larger than the sum of its proper divisors (1691489).

3805821 is a wasteful number, since it uses less digits than its factorization.

3805821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422875 (or 422872 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 3805821 is about 1950.8513526151. The cubic root of 3805821 is about 156.1287152671.

The spelling of 3805821 in words is "three million, eight hundred five thousand, eight hundred twenty-one".