3869821 has 4 divisors (see below), whose sum is σ = 3875872. Its totient is φ = 3863772.

The previous prime is 3869807. The next prime is 3869849. The reversal of 3869821 is 1289683.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1289683 = 67 ⋅19249.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3869821 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 (3869861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1935 + ... + 3388.

It is an arithmetic number, because the mean of its divisors is an integer number (968968).

Almost surely, 2^3869821 is an apocalyptic number.

It is an amenable number.

3869821 is a deficient number, since it is larger than the sum of its proper divisors (6051).

3869821 is an equidigital number, since it uses as much as digits as its factorization.

3869821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6050.

The product of its digits is 20736, while the sum is 37.

The square root of 3869821 is about 1967.1860613577. The cubic root of 3869821 is about 156.9990263236. Note that the first 3 decimals are identical.

The spelling of 3869821 in words is "three million, eight hundred sixty-nine thousand, eight hundred twenty-one".