3915821 has 16 divisors (see below), whose sum is σ = 4953984. Its totient is φ = 3011904.

The previous prime is 3915817. The next prime is 3915823. The reversal of 3915821 is 1285193.

3915821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 3915821 - 2² = 3915817 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3915823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2786 + ... + 3948.

It is an arithmetic number, because the mean of its divisors is an integer number (309624).

Almost surely, 2^3915821 is an apocalyptic number.

It is an amenable number.

3915821 is a deficient number, since it is larger than the sum of its proper divisors (1038163).

3915821 is a wasteful number, since it uses less digits than its factorization.

3915821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1220.

The product of its digits is 2160, while the sum is 29.

The square root of 3915821 is about 1978.8433490299. The cubic root of 3915821 is about 157.6186525073.

The spelling of 3915821 in words is "three million, nine hundred fifteen thousand, eight hundred twenty-one".