3847821 has 4 divisors (see below), whose sum is σ = 5130432. Its totient is φ = 2565212.

The previous prime is 3847817. The next prime is 3847829. The reversal of 3847821 is 1287483.

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: 1287483 = 3 ⋅429161.

It is a cyclic number.

It is not a de Polignac number, because 3847821 - 2² = 3847817 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3847829) 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, 641301 + ... + 641306.

It is an arithmetic number, because the mean of its divisors is an integer number (1282608).

Almost surely, 2^3847821 is an apocalyptic number.

It is an amenable number.

3847821 is a deficient number, since it is larger than the sum of its proper divisors (1282611).

3847821 is a wasteful number, since it uses less digits than its factorization.

3847821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1282610.

The product of its digits is 10752, while the sum is 33.

The square root of 3847821 is about 1961.5863478318. The cubic root of 3847821 is about 156.7009466760.

The spelling of 3847821 in words is "three million, eight hundred forty-seven thousand, eight hundred twenty-one".